I'm still tackling some of the side-content, and also going back and cleaning up quests I never completed before. Honestly, I found Endwalker to be an... interesting experience. I've said before, I liked the story, just that to me, it felt like Zodiark got wrapped-up way too quickly, and the Moon didn't wind up being terribly interesting or important.
Looking towards the future, I'm hoping for one of a few possibilities:
1. One option, which I would LOVE, is to take a "second stab" at telling the story of Zodiark and Hydaelyn. Venat was cool, but as some have pointed out, maybe less "motherly" and "loving" than Hydaelyn seemed. I would love to see Hydaelyn fleshed-out a bit more, and actually giving Zodiark a personality.
Like, maybe Zodiark also loved the people of Etheris, but HIS approach was to begin re-shaping their bodies to be better-suited for war, to go out and CONQUER the cosmos before anyone could pose a threat. Hydaelyn had to restrain him, and sought to keep our humanity, thus the fusion of both of their powers' giving birth to the Playable Races (maybe Garleans, being the product of Emet-Selch, lacked aetheric ability because they lacked that connection to Zodiark and Hydaelyn?).
So maybe without Zodiark OR Hydaelyn around, aether goes out of control, maybe Primals begin manifesting sponteneously, thus requiring us to re-summon BOTH of them, thus achieving balance?
2. Just us "Adventuring" again! Honestly, I dug being "the Warrior of Light, savior of the universe", but I wouldn't make going more low-stakes with some one-off adventures! For example, maybe we catch up with each of the Scions, and just do some slice-of-life stuff with them. Like maybe Y'shtola decides Matoya needs a nicer living quarters, and we help them build a proper little "wizards' tower" that's no longer secluded? Or do some catching-up with old quest NPC's?
3. Mo' stuff on the Moon! Honestly, even if we aren't outright exploring the entirety of the Moon, I feel like it would be cool just to visit, and maybe make the whole place a little more pleasant?
Like, for one, I feel like we should inherit the Watcher's Tower (unless the aforementioned point of Zodiark and Hydaelyn coming back and working more in unison, in which case I'd love for that to be their sort of "home-base"). That crater where Zodiark was imprisoned looks hella sketchy even now, and honestly? I think it would be cool if we could sort of "cleanse" the space, maybe even creating some kind of "aetheric biome" to have a small field of flowers (Elpis flowers, perhaps?), just making the Moon more of a "pretty" location.
Similarly, I'd love to work WITH the Loporitts, and have Bestway Burrow COMPLETELY transform! Instead of the harsh, empty Allagan-like design it currently has, maybe we help them draw inspiration from various parts of Etheiris, that each "section" becomes populated with an entirely new look, maybe even creating their own "sky" sort of like Labrynthos? Barring that, just making the place a little more pleasant to visit, and ESPECIALLY taking advantage of the MASSIVE space that makes up Bestway Burrow. Heck, maybe the Loporrits even decide to make it like "a rabbit's paradise", giant woods and little burrows everywhere, vaguely a "Winnie the Pooh/Hundred-Acre Wood" vibe?
4. Deeper "Primal" lore. I used to love learning about Primals, but after Heavensward, it just sort of felt like "primals are just make-believe beings given form via aether". Yet I still always recall Ifrit speaking to us, with that line "Thou are strong, mortal". It always felt like they deserve a bit more history. I haven't counted how many primals exist, so I assume more than there are members of the Convocation, but it would be cool if maybe there is some small part of primals that is connected to something truly ancient, that while INFLUENCED by their summoner(s), they ultimately have some personality and memory of their own. So maybe Venat and Hydaelyn were connected by their love of Etheris and its people, but are actually two different beings with their own slightly differing personalities?