It was because of what Ysayle used to power up Shiva in her. She was ready to die the moment she feed Shiva with the aether of her own Light Crystal.
My predication as others have stated, a we find a Scion in each patch with Minfilla being last. After we find all the Scions that will lead us into the next expansion which that could be anywhere depending on where they take the story at.
A lot of people believe, including myself, that the next expansion may be Ala Mhigo, and maybe the Garlean Empire region as well depending on the size of Ala Mhigo's maps, since we now have cover the City State of Ishgard and Sharlayan(or what is left of that place). Not to mention the story so far seems to be pushing for the next Garlean Comflict with all City-states now united to face the Garlean Empire's Threat, Ilbert preparing to give up anything to set Ala Mhigo free from the Garlean Empire, and the Garlean Empire now have a new Flagship to lead their army once again.
The Flagship may be repaired some time in 3.X era which may lead to it becoming the new head of the next Garlean Assault on Eorzea.
-One scion rescued each patch. It's a FF game and it was clear by the ambiguous nature of their "deaths" that they weren't going to kill any of them off.
-We will "save" Estinien from being Niddhog, but unclear whether he will live or die after we do so. Most likely he'll die after reverting back to Elezen form.
-Garlond will continue their research on Azys Lla. Not sure what new scheme they'll hatch since they now know that primals cannot be permanently destroyed.
I'm still wondering why we didn't search for Thancred after finding Y'shtola.
I'm almost certain that Minfilia is playing the damsel in distress somewhere
Yda and Papalymo either escaped and are in hiding or are being held captive somewhere (probably the same place as Minfilia).
So we'll either have one big patch, rescuing them all, or It will be spread out across several patches.
I won't be too surprised if "saving" Estinien will involve Ysayle somehow, to mirror Shiva and Hraesvalgr's relationship.
I feel kinda dumb asking... but is it Estinien in this fankit image from ARR? We know he got possessed by Nidhogg, but this makes it look like the Ascians are involved as well.
http://img.finalfantasyxiv.com/lds/p...jpg?1425023002
I'm still holding out onto hope that Gaius is not actually dead, and will come back and start a full-blown civil war with the Empire. Judging from all the fanatical "Retake Ala Mihgo" NPCs I've seen and had to deal with and the way they all behaved, AND the fact that the bandits around Little Ala Mihgo are the remnants of the old ruling guard, I'm suspecting we'll never "take back" Ala Mihgo, and even suspect that the people still there prefer Garlean rule under Gaius as opposed to their previous rulers.