Zenos is... [big fat spoily]

[Silvarer]

Many things, actually! Especially now that he took the time to travel to Sharlayan, not to attack people but to find a way to help us. (I'm forever salty I did not get to see what he said and did in Sharlayan). At the end he asked the WoL "Did you find fulfillment?" and then he said "I..." and died. This is up to the player, but I think he wanted to say he did not find fulfillment after all and he realized that fighting us endlessly for a moment of happiness is pointless. He was actually quite disappointed because he lost again. Plus he was the one who helped us get home, a suprising act of selflessness.

And then there's the thing I linked in a previous post: why did Zenos dream about the Final Days and how is Emet-Selch involved? I have so many questions. They also never mentioned his lonely childhood in the game, only in an official book. Why was Varis so cold to him? Is it because he was an a-hole or is there something else to that story? There's a fan theory that Zenos is somehow an experiment of Emet and that's why Varis never loved him. Who knows? Zenos is a mysterious character and SE could do so much more... There are many possibilities.

They clearly didn’t care enough about these possibilities to actually do anything with them in the three expansions he was in so I don’t know why you think it would be worth keeping him around for more. Also he didn’t go to Sharlyan with the intention of helping, he simply wanted to find us. If you pick the option “I don’t want your help” he even flat out says he’d rather not give it because he doesn’t care anything about that kind of stuff.

[TheMightyMollusk]

And he did many fun things in the expansions, there's always room for more.

Yeah, remember how he killed messengers who brought him bad news, and brutalized two entire nations just looking for someone to fight, and tortured Krile for mad science, and hijacked a dragon just to make a fight bigger, and killed himself, and then killed his dad, and started an apocalypse? Good times, good times.

[Silvarer]

He did help tho. He helped us chase down Meteion to get rid of the threat so he can have the WoL's attention. And he helped us get home with his last wish. And he did many fun things in the expansions, there's always room for more.

If you consider doing things like stealing your body or killing his own people just for his own selfish desires fun then that’s a mindset I can’t understand. If you wanna drool over him then whatever, but I can’t stand him. If they bring him back yet again just for the same “But I wanna fight you” crap then it’s going to be really dumb.

[Drkdays]

Give me a real rival, not this dimwitted, attention-seeking, egomaniacal, Karen of an enemy. I want a Thanos type of rival; someone I can relate to, understand, even empathize with but whom I am still completely at odds. Someone I dread facing, not because he has flashy techniques but because I know he is dedicated to winning at all costs. Someone whose ideallogy, intelligence and willpower are just as threatening as his daunting personal power.

Calling Zenos a rival is a lame joke. "Self-described" rival, more like.

[Lord_Umbra]

Considering this is FF4 expansion & Zenos is fairly identical to a certain Goldbez I too doubt he is actually dead. Also we know Zenos can't control his resurrection as even he was surprised to live in SB & based on Reaper questline it feels like he would've you know exploded into void dust like the Reaper Job quest, I fully expect a Goldbez turn with him changing & becoming a kinder good guy.

Still la lot of mystery around Zenos such as what experiments did Varis do to him when talked about Zenos being nothing but a Experiment/monster or Fan Daniel talk about whatever Emet may have done to Zenos "could Emet found a way?" plenty of stuff to delve into with Zenos. Also what's with people assuming he used up all the mother crystal energy to get there/fight us he may still have reserves & even if that is the case I imagine he can easily control all the Dynamis in that zone.

[Enkidoh]

Also what's with people assuming he used up all the mother crystal energy to get there/fight us he may still have reserves & even if that is the case I imagine he can easily control all the Dynamis in that zone.

Zenos consumed what was left of the Mothercrystal to turn into Shinryu and to travel to the Dead Ends - and that he needed to use every last drop of aether it gave to do so (notice he actually did not help the WoL with the Endsinger but merely acted as a stage for the fight?) - remember the Ragnarok needed to use up most of the Mothercrystal to do the same thing.

And afterwards, Zenos himself outright tells you that "he will have to burn through the candle of his life" to face the WoL, he was basically saying then and there "this will end me, but as long as I get my glorious battle with you, then I will die happy." And that is exactly what happens. He might have had some left over 'Mothercrystal' aether within his body for his last battle, but I pretty much doubt it.

The fact SE actually had him state that made it pretty clear that is exactly what takes place, it's pretty clear cut. He's gone and is not coming back.

[Iscah]

Further on the tangent of whether "Etheirys" should be the term for the modern world or only the unsundered world – I'm replaying the level 84 moon quests at the moment, and Urianger starts calling it Etheirys (talking about the view of the planet from the moon) as soon as the Watcher introduces the term. Also the Loporrits call it Etheirys despite being created by Hydaelyn post-sundering, so apparently she intends to keep calling it that.

If there's a specific origin to calling the planet Hydaelyn, I would suspect it was the Sharlayans who started it after making contact with the so-thought Mothercrystal at the heart of the planet and incorrectly conflating the two.

[Abomination713]

So here's my take on it. He's still alive and will show back up out of nowhere in a brand new clone body since Garlemald has perfected cloning technology and even Emet-Selch had multiple cloned bodies just laying around for him to use when he died. He will be satisfied with the fight we had, but now it's no longer about having the best fight every. It's now about winning that fight as he views it as overcoming the one challenge he as ever had in his life. A goal he can aim for. In order to do this he will journey around the world in our company and help us in the new challenges we will face. If he and his method did not work in beating us, maybe seeing how we live our day to day life and following what we do is the key to finally pushing past his limits.

Yeah, it's dumb, but no one dies in this game when they should.