https://www.reddit.com/r/baldursgate/comments/fhk8iw/the_official_larian_ama_is_live/4. There have been hints of other 5e sources being implemented into the game. Are you going to include material from Mordenkainen's Tome of Foes, Xanathar's Guide to Everything, and/or other player materials outside of the core material of the 5e Player's Handbook? Additionally, at full release, will all content of the PHB be represented (notably, (sub)classes and (sub)races)?
HB/MM/DMG are the base we are starting from but we are taking material from other books too.
People often misstake it with this one:
Will all 5e Classes be available at launch?
> Yes, all classes from 5e Player’s Handbook will be included at launch. In Early Access you’ll be able to play as a Cleric, Fighter, Ranger, Rogue, Warlock or Wizard.
Does that include paths, subclasses, etc?
> Yep.
Prof. Dr. Dr. Mad S. Tist 
