Predictions for 5.3?

[Archwizard]

I mean 5.3 has to unveil someone/something as a new adversary for a chapter two set up.

There's already an implication of a new adversary within Shadowbringers' own climax.

Something caused the Amaurotians' powers to go haywire. A Sound from within the planet led to the creation of the First Doom, and began a cascade of terror that heralded the end of a world.
In classical Final Fantasy fashion: "Oh, these obvious villains you've been fighting since day 1? They're actually extremists pushing back against something much worse, and the rest of the world is just caught in the middle. Since you killed them all, that enemy is now unopposed, setting up the true final boss. Nice Job Breaking It, Hero."

I'm not sure we'll be fighting Lavos specifically (since 14 is a celebration of the entire FF series and Chrono Trigger is just a bit outside that purview)... but that is an interesting theory.

That said, I expect the core of 5.3 will be about wrapping up our involvement in Norvrandt more than dealing with the Ascians themselves. No doubt that we'll fight him again, but to just kill off Elidibus now would feel like kind of a hasty wrap-up on a multi-expansion arc (and extremely soon after Emet-Selch), particularly given how Stormblood was a drought for Ascian content and we've only just learned their motivations.

Besides, Yoshi-P said we wouldn't guess who the trial boss is, and Elidibus is easily the most obvious choice for a big wrap-up trial.

[Riastrad]

I mean, right? I can see us fighting Elidibus ( I really don't want to just off him and be done with the ascians) and it being a trial. There just has to be something more than that. He just got back into the story and I would rather they explain him instead of killing him off. Moenbryda springs to mind and I would rather not have a repeat of that.

As for Lavos, I said it before, I just can't see references to FFVIII and not think about the other game Square put out later in the same year. Especially when it also dealt with reality traveling (expanse contract) and time compression (eon become instant). My brain just isn't wired to ignore it. Heck there are other posts in this thread by me that also put forward visual similarities. I'm not saying it's 100% accurate, just that it is what it is, a personal theory.

[Crushnight]

Between Meracydia and Sharlayan, Sharlayan is the far more likely candidate to me.

1. Its msq focus was far greater than Meracydia in HW, Meracydia had Tiamat's dialogue only even the warring triad was not mentioned as Meracydian until side story with Unakalhal whereas Sharlayan had;
-Forbidden spells and spell experimentation (Flow to the now used Teleport)
-Motto (Knowledge seek no man)
-Thier culture (architecture/sentries/government)
-2 dungeons Gubal and more importantly Antitower, I find it very likely that Sharlayans would've built a second tower closer to home perhaps one that runs deeper into the Aetherical sea (probably best way to get to Hydelyn and thus Zodiark because right now, how do we get to the moon? Meracydia would have to have an Allagan rocket or something)
-Master Matoya's crystal eye, I doubt she has the only crystal of light from another era, especially since Krile knew what it was while Y'shtola didn't.
If we add side story than Meracydia has a bigger emphasis but still pails in comparison to Sharlayan as you have to add Ast questline and how ruthless they are about not sharing certain knowledge and Saint.M's dungeon so plant life experimentation vs Meracydia's 2 beast tribes (Trees/centaurs), and the warring Triad.

2. Meracydia's size is as big as the 3 great continents, this fact alone screams that it would take multiple expansions to deal with what Meracydia can offer and I would want that, Meracydia has a lot going for it and I would want it to have the love and care Ishgard and the 1st has had.

3. Sharlayan's size is much smaller and a split expansion focus with it and Garlemald is going to be far less hazardous especially when we have a much more established area compared to Meracydia.

Those are my basic reasonings, I want to go to both Sharlayan and Meracydia, both sound like very interesting places to go, I just think Meracydia would be too disjointed at this current stage or it would suffer the same way Ala Mhigo did. (As I currently think we will get an Emporer primal in Garlemald based on how the Empire is taught to revere him, the civil war going on, the alliance at their doorstep, it's all a recipe to make an primal desperation of the masses, faith, the only thing missing is power source but given that it is Garlemald and their association with the Allagan Empire not going to be too hard to find one I think).

[JeanneOrnitier]

Garlemald is definitely next, so if somewhere else is going to share the spotlight with it ala Stormblood, I agree I'd rather it be Sharlayan. I'm super interested in Meracydia and don't want it getting the Ala Mhigo treatment (though I also would think/hope Square has learned not to divide the spotlight so unevenly after StB).

[EdwinLi]

Garlemald is definitely next, so if somewhere else is going to share the spotlight with it ala Stormblood, I agree I'd rather it be Sharlayan. I'm super interested in Meracydia and don't want it getting the Ala Mhigo treatment (though I also would think/hope Square has learned not to divide the spotlight so unevenly after StB).

Considering now Garlean Empire's capital city is in a sea of fire due to Civil War for leadership of the country and the current side storylines are basically about mopping up the remaining Garlean Forces that are a threat the the Alliance on Eorzea and Doma side of events, I will be surprised if Garlean Empire is not part of the next Expansion since there is basically no Garlean Empire left but just fragments trying to hold on to what fragments of the Empire they have.

[Rocl]

Garlemald is definitely next,

I would've lost a lot of money betting on Ilsabard being 5.0 before 4.4+ >_>

[Cilia]

A recent interview of Yoshi-P on GameSpot says almost verbatim they'e going the (in)famous "subverting expectations" route and that we should "get a refresher on Heavensward" going forward.

Make of that what you will, but I seriously doubt Garlemald / Ilsabard is up next.

[Archwizard]

1. Its msq focus was far greater than Meracydia in HW, Meracydia had Tiamat's dialogue only even the warring triad was not mentioned as Meracydian until side story with Unakalhal

I wouldn't say any of Sharlayan was "focused" on in Heavensward. Tangentially referenced in many cases, but no more of a "focus" than Meracydia.

If you're going to use things as vague as spells and mottos as evidence of a "focus", then you could just as easily argue that the entire zone of Azys Lla is a huge reference to whatever the Allagans were doing in Meracydia, that Mhach is a good example of what the Voidsent the Allagans unleashed would have done to Meracydia, and that Midgardsormr and the First Brood make up a central part of Heavensward's story, which are a lot more substantial than many of the references you're making.
We also learn from the Warring Triad story that Sophia was summoned by a convocation of Meracydia's civilized races (including whatever race the Demiurges hailed from), and from Tiamat herself about how the Ascians manipulated her brood into summoning Bahamut, bringing Dalamud back around into the story. It's unlikely the Allagans shoved the entire dragon population of Meracydia onto one vessel, and quite probable they still have a handful waiting for Tiamat's return (which could make another solid substory and potential beast tribe).

I would also like to point out that the Warring Triad, Alexander and Mhach were not directions many people would have expected out of Heavensward just based on knowing we were going to Coerthas and getting involved in the Dragonsong War, much as Ivalice and Val were for Stormblood, or NieR was for Shadowbringers. To imply there wouldn't be enough side story content is really grasping for straws.

2. Meracydia's size is as big as the 3 great continents, this fact alone screams that it would take multiple expansions to deal with what Meracydia can offer and I would want that, Meracydia has a lot going for it and I would want it to have the love and care Ishgard and the 1st has had.

First I'm hearing of it being that big. Last I heard all we knew about its geography was "it's south of Eorzea".
We know it put up a massive resistance to the Allagans but that doesn't necessarily have anything to do with landmass. It's not on any recent maps, but on renders of the planet it appears to just be one big island smaller than Aldenard. About the size of Eorzea itself, really.

Bear in mind that:
1. Individual zones from expansions are bigger than zones from ARR, largely since they were built with flight in mind. Norvrandt is canonically the size of Eorzea, and we explored all of its relevant landmass in 5 zones. (Though it is worth noting that there appears to be a huge amount of space left to cover just on the island of Kholusia, given the NieR raids, and that our characters travel quite a while between zones within expansions, none of which is rendered.)
2. Othard is an entire continent unto itself, and we've only explored 3 zones of it; some of the largest expanses of it, like Rabanastre or The Burn, were relegated purely to dungeons. Even Coerthas only gained 2 zones in Heavensward, with the rest of its expansion covering Abalathia's Spine and Dravania.
3. We know next to nothing about Meracydia itself or how badly the Allagans scarred it, giving the devs complete freedom for what to do with it. For all we know 90% of Meracydia is Burned and we would only hypothetically explore a fraction of it. Even so, an expansion's worth of zones and dungeons would still be plenty to cover its relevant mass.

At any rate, you could use the same arguments to delay Meracydia indefinitely, "It's too big to explore all in one expansion," just as you theoretically could have with The First before Shadowbringers.

[Morningstar1337]

I wouldn't say any of Sharlayan was "focused" on in Heavensward. Tangentially referenced in many cases, but no more of a "focus" than Meracydia.

I mean they are the reason the Hinterlands (and Idylshire by extension) had any ruins and were likewise the creators of the Antitower and Gubal. A zone, an endgame hub and 2 dungeons was more for them than what we have for Meracyida.

Plus I think we know more about that then we do Meracydia, enough that I've been wondering if they are gonna be the next not-as-cosmic antagonists after Garlemald (due to their hoarding of knowledge and the likelihood that there are some there that would like to use it for nefarious ends), in contrast to the more cosmic Ascians and the sound.

[Archwizard]

I mean they are the reason the Hinterlands (and Idylshire by extension) had any ruins and were likewise the creators of the Antitower and Gubal. A zone, an endgame hub and 2 dungeons was more for them than what we have for Meracyida.

Plus I think we know more about that then we do Meracydia, enough that I've been wondering if they are gonna be the next not-as-cosmic antagonists after Garlemald (due to their hoarding of knowledge and the likelihood that there are some there that would like to use it for nefarious ends), in contrast to the more cosmic Ascians and the sound.

And I would disagree completely.

What we know of Sharlayan:
- The Circle of Knowing, Sons of Saint Coinach and Students of Baldesion studied there a while back years before the Val incident, and they're big on academia and the study of the Lifestream, with Thaliak as their patron god and the implication they know more about time magic than they let on
- A conservative faction within their government pushed to make sharing their magical knowledge an act of treason, to the point they're willing to assassinate wayward Astromancers
- They previously expanded out into Dravania but abandoned it when Garlemald first invaded because they're non-confrontational, so they returned to the Old World and now they're isolationist; Matoya is probably the last Sharlayan scholar remaining in Dravania, and is tasked with overseeing the most powerful artifacts they left behind such as the Antitower

What we know of Meracydia:
- Bahamut and Tiamat's brood grew out of Meracydia, until Xande murdered Bahamut during the conquest; the Ascians taught the Meracydians about summoning, and the Allagans how to use Omega to imprison Bahamut's primal copy within Dalamud with thousands of his tempered children; the Burn was likely a result of siphoning aether in order to launch Dalamud, though the Garleans blame it on summoning instead
- Their native races - including tree people, centaurs, and a myriad of civilized races - were responsible for the Warring Triad, which were imprisoned within Azys Lla, along with several trophies of war and objects of research; the Ixali came about from some of this research in Azys Lla, as well as several prototypes for what would become the Ultima Weapon
- Xande's clone was so desperate to conquer Meracydia that he contracted with Cloud of Darkness, sent out an army of Voidsent to possess the fallen, and used the Crystal Tower to siphon power from Dalamud and rip open a portal to the Void, causing the Fourth Umbral Calamity
- The wake of the Allagan invasion left most of Meracydia a wasteland and drove several of its native races to build the Far Eastern nations; however, it's still not entirely unpopulated, with hostile and reclusive colonies in the remaining habitable areas, while witch doctors from Meracydia continue to trade with Eorzeans for ingredients for their potions

There's as much to draw from based on what we know of Meracydia as from what we know of Sharlayan - if not more.

Further, I'd say most of the Dravanian Hinterlands was sort of... incidentally Sharlayan. Like yes, there are ruins there, but outside the dungeons they're given a "That's neat" sort of reaction as you walk past mossy rocks with patterns carved in.
You have 3 dungeons and a town that were made by Sharlayan, but they also have next to nothing of Sharlayan anymore, because they're overgrown and coopted by the things that have populated them since. They're architecture now and little more, next to no delving into the implications they had upon the society at its peak. The Arboretum tells you nothing, Gubal Library tells you nothing in the grand scheme you didn't already know, and the Antitower's strongest implications are on its imminent plot relevance rather than the nation that originally built it. It's not about "how many ruins are there", it's "what's the value of information you can get from it"; the Hinterlands could just as well be a desert and you'd learn as much from everything outside Matoya's cave. And all she'll tell you is they're cowards and can suck it. The Hinterlands use the Sharlayan ruins as a setpiece for largely unrelated stories.
Azys Lla is populated largely of artifacts and creatures STOLEN from Meracydia, most of which are still preserved in two of its dungeons and three trials, some of which can and do give firsthand accounts of their homeland or feature visual "twists" to the story. Every moment you're in Azys Lla, you are hip-deep in the Allagan-Meracydian conflict; you cannot turn a corner without asking yourself something new about the country. You get as much about the Meracydians from Azys Lla as you do about the Ascians from Amaurot. The weight of information on Meracydia from that one zone is still higher than the information on Sharlayan from all the others combined.