The engine and it's assets should be used for something new in Forgotten Realms.
An expansion to BG3 could work, maybe. But the standards they have for the companions are very high. How to continue their stories from BG3 ending?
What I would like is smaller new adventure modules. With less cinematics and voice acting. Something faster to produce with a multiplayer focus. No big companion storylines or infinitely branching storylines. Just a module for 4 players to play through together. Or single player where you create all 4 characters.
It would be cool if someone would license the engine to make Icewind Dale 3 or a Dragonlance game.
It could be a good idea, one or two 100 hours expansion Icewind Dale Style, so you can reach 20 level, no default companions with storyline, you create your party from scratch. In the DLC Larian corrects all bugs players are finding in the game and apply the best ideas we provide here in the forum.
Then BG4 (with ray tracing, DLSS 3/4, night and day and so on).