What's the point with that quite lackluster story in Endwalker?

[Kozh]

The Garleans have long been the only significant source of strife on the Three Great Continents outside of civil wars like those in pre-occupation Ala Mhigo, so unless there's some closet military power hiding in Ilsabard and waiting to make their presence known, I have trouble thinking of who/what else could realistically serve as the antagonist for an Ilsbard expansion barring the introduction of some new supernatural threat as a consequence of Endwalker's events changing the natural order.

Maybe they could use some resistance extrimist for the new "antagonist"? Or perhaps since Garlemald is no more, the nations/regions start going into civil war to seize due to lack of common enemy. Personally I don't really need a super military power as our next enemy.

And your idea about the new supernatural threat is good too.