Do you think one of the Scions will die on Dawntrail

[Cleretic]

Y'shtola will never die because they use her as exposition dumper since the player is too stupid to figure out the plot themselves.

So this is also an element of the Scions that I think is interesting and leads to making them constant characters: they act as broadly present and trustworthy Exposition Dumpers for specific types of information. If we're meant to know or learn a fact about the world that isn't necessarily a mystery to figure out or otherwise warrant dedicated gameplay, the Scions act as reliable sources, that we can trust will be telling us the truth. And a lot of them kinda have their own field, that sometimes overlap.

Y'shtola's our broad Magical Knowledge person; she's a walking science textbook.
Alphinaud has over time become the Politics Boy, he produces the sort of dry, theoretically available but important information that's helpful for a political plotline.
Thancred provides an interesting alternative angle to Alphinaud, in being sort of the 'spycraft' character; if Alphinaud is essentially the Wikipedia article on a country, Thancred's the one that digs deeper and finds info that isn't publicly available. A broadly similar knowledge base, but you wouldn't substitute one for the other directly.
Krile (who I forgot about in my last post) is... basically a backup Y'shtola, their knowledge bases don't differ in practice.
Urianger is kinda the Thancred to Alphinaud's Y'shtola: he's also a magical knowledge person, but his expertise comes in the esoterica that most people wouldn't know. Y'shtola's a walking science textbook, Urianger's a walking 'fourth page of google search results that finally have what you REALLY wanted'.
Tataru is a solid accountant and money person; understandably this didn't come up very often.
Estinien's broadly not this same sort of character, at least from design intention, but he does have the knowledge set of 'combat, war, dragons'; out of all the Scions, he's the guy that can tell you if a military's good or not.
Alisaie... well,
G'raha I think was kinda supposed to have an 'Allagan tech' specialty, but he only joined the main cast after Allag stopped being a big deal, and it's more fun to find a more dedicated expert for other forms of tech like electrope, so he's kinda just wound up as another backup Y'shtola that gets to say 'Crystal Tower' sometimes.

You can occasionally just not need a few of these so they'll just sit out an expansion (see: the magic types not being part of Stormblood), but if you were weighing the pros and cons of actually killing a Scion this is another element; the purely functional story aid. If Alphianud died, and we needed someone broadly trustworthy to tell us about local trade deals or something, what do we do?