Everyone was expecting Garlemald / Ilsabard in the lead-up to Shadowbringers, given it was the last unexplored part of the Three Great Continents and the engine of conflict driving most if not all of the story, in addition to its leader now having an excuse to go on the offensive against the rest of the known world.
Instead they took an Alliance raid, two raid storylines, an early 4.0 sidequest, and mixed them with the ubiquitous Ascian influence, then shipped us off to an alternate world.
Nobody has much of an idea as to what's going to happen beyond 5.3 or why at the moment; only the nebulous hints that they will be "go[ing] against players' expectations" and to "get a refresher on Heavensward." Make of those what you will.