The amount of assests and systems BG3 has, but hardly uses as the game rushes past them full of things. There's potential for a dozen adventure modules/DLC storylines to be added on, either in game (i.e. Fallout dlc) or stand alone with new PC (ala NWN2's dlc) to add hours more gameplay to this game without really needed much in the way of new assets or code, just reusing the current in different combinations + new writing/VA work.
BG3 has so much potential for expansion, it'd be a waste if they moved on to anything new or settled with just improvements and restoration to the visions cut.