What's with Y'shtola's vision?

[Adeacia]

She is blind. She uses her own aether to help her see things. Everything is made up of aether. It's why Matoya tells her that it'll kill her one day. Though so far the devs haven't shown what kind of toll it's been taking on her. She probably just wanted Urianger to give a poetic version of what the night sky looked like on the 1st. These types of questions are best suited for the Lore section of the forum. I do believe there was/is a thread that talks about this topic in that section.

This here. Also, though Matoya did say that, there was no timeline given. It could simply mean she'll leave 5 years less then the average lifespan of her kind. It's not something that actually has to be directly addressed in the story itself.

[Nothv13]

This here. Also, though Matoya did say that, there was no timeline given. It could simply mean she'll leave 5 years less then the average lifespan of her kind. It's not something that actually has to be directly addressed in the story itself.

I recall that it was really only the English translation that said it would shorten her life, though I could be wrong as I don't speak the other languages.

[Liam_Harper]

This here. Also, though Matoya did say that, there was no timeline given. It could simply mean she'll leave 5 years less then the average lifespan of her kind. It's not something that actually has to be directly addressed in the story itself.

They do deliberately mention it takes a toll on her lifeforce though, in story telling it would be strange to mention something like that and do nothing with it. I expect it will come up again, there have been plenty of things in the story they've brought up, then concluded several expansions later or more.

I doubt they'd kill her off, she's in enough of the story to have plot armor at this stage, but my guess would be it will start showing effect when it comes to the final battles in Endwalker. That's sure to be a lot of strain.

[Adeacia]

They do deliberately mention it takes a toll on her lifeforce though, in story telling it would be strange to mention something like that and do nothing with it. I expect it will come up again, there have been plenty of things in the story they've brought up, then concluded several expansions later or more.

I doubt they'd kill her off, she's in enough of the story to have plot armor at this stage, but my guess would be it will start showing effect when it comes to the final battles in Endwalker. That's sure to be a lot of strain.

I've seen plenty of stories have situations like this, but it doesn't take its toll until after the story ends. Says what happens to them during the ending. Wild Arms 4 is an example. One character has some kind of condition that will kill her sooner rather than later. It's brought up many times in the story, and during the ending it explains that she only lives for a few years after the story concludes. The Suikoden series is also good for this kind of thing. During the ending it shows what happened to every single one of the possible 108 characters you actually recruited after the story ended.

While it's true that being this is an mmo that format may not work quite as well unless its done properly, it's still a thing that can be done.