I always thought that this expansion would be the one that we go fully against Garlemald to finish its empire, but apparenly we'll have more like a "sidequest-esque" expansion regarding that matter (not that this makes it lose importance or anything). So, in the wake of this fact, I think that our and the Scions absence from the Source for so long will allow the Garlean Empire to fully wreck havoc to Eorzea, and when we return, we'll find that mess. This will probably be a later portion of the expansion as a build up for 6.0 being what I thought 5.0 would've been.

Also I really expect/want that this whole set of events in ShB turn out to put both Zodiark and Hydaelyn in a gray zone, and we won't belong to either but our own.