The plus here is that Larian is essentially creating a 5e Engine. Much like the Infinity Engine spawned an entire genre of games in the late 90s/early 00s based around RTWP, party-management, 2D world exploration, and an isometric perspective, this engine offers the potential for diverse experiences with Turn-based Combat, story cinematics, 3D world exploration, and a quasi-isometric perspective. Independent of what you think about the execution of Baldur's Gate 3, the raw ingredients for other 5e experiences are already here, in a very well-polished engine (relative to its competitors). Supposing BG3 comes out and Larian catches flak for a handful of game elements or mechanics, it is entirely possible they might switch directions in some areas. Providing a new setting keeps the content fresh, granting a new experience while using the same engine.
The situation is a bit different then in times of Infinity Engine - while Bioware created the engine for what became Baldur's Gate, they were working closely with Interplay and that relationship resulted in couple Interplay lead projects. Larian doesn't have such association - they get licence from WotC of course, but I would be surprised if all that they create wouldn't be theirs to keep. That said, they already greenlit a side project like that before - there was a tactical RPG to be made using D:OS2. In general, Larian doesn't seem to have luck with hired help - from what I understand the title I mentioned got scrapped, and Divinity board game seems to have troubled development as well.
No one comes to my mind, who could take an advantage of Larian's engine - all potential candidates have been bought up Microsoft, so an allience is unlikely. One could dream of Solasta team using BG3 engine, but they would need to upscale greatly to take advantage of it - and from what I understand they are not interested in that.
