Larian Studios now have a DnD 5e game engine to make new games with. They also have created a lot of graphics in the Forgotten Realms. They can now make new DnD games with much less effort than making BG3 from scratch.
If I recall correctly Larians Studios got a license from Wizards of the Coast with rights to make multiple games in the Forgotten Realms. So it's definitely likely we will see more DnD games from them. Whether we will get an expansion or not will be determined about how BG3 ends. I guess we will see then if the story of the current characters are finished or not. Personally I wouldn't mind seeing expansions giving us a chance to continue the journey, but I could start fresh with a completely different story as well in their next game.
I also think it's natural that Larian Studios will eventually develop functionality to increase the level cap. Maybe not for BG3, but for the next main Forgotten Realms game they will make.
