Also based on the interviews I guess this is gonna be another case where at least on launch the max level exclusive zones are subzones of the 4. Even more so since they stated that as we upgrade our dragonriding we will be able to access new areas. I mean depending how they pull off the max level subzones. But a max level exclusive zone is a safe bet and weird not to do it. I guess BFA didn't have one (except revamps until 8.2). We might have the badlands be revamped with the uldaman dungeon tho.
But yeah, I really hope they aren't overhyping the huge zones in size. Like it would be cool if we got the 4 zones together to be the size between mop (7 zones on main continent without surrounding islands for patches) and wod at least (again 7 zones including tanaan since it is on the main landmass).
Having a single zone be almost 2x a mop or draenor zone could be cool. And it kinda makes sense what they were saying about it needing to be bigger as it is the homeland of dragons.
Still we have barely touched the surface I believe of what will be populating those zones, at most we saw half a dozen of the friendlies/enemies