They have not stated much. They said that they are mainly focusing on PHB, DMG, and MM, but also are looking at other books (yes, just that vague). And they have said "all PHB classes and subclasses will be in, but we're only talking about the revealed races for now."
Thanks! Considering Wizards looks to get subclasses for all eight schools of magic implemented, having just the two PHB subclasses for some classes seems a bit unbalanced. Crossing my fingers for a revised Ranger Gloom Stalker.
The level 20 version of this build has some levels of gloom stalker, such an amazing subclass.
The Legolas and munchkin in me is drooling in anticipation lol. Won't plan that far ahead given the level cap of 10. Want a build that comes on line fairly quickly and that stays strong throughout. Fully expect a sequel for those high-level builds though!