I've never played DOS, but what I'm wondering all the time is if it wouldn't be a dream of Swen's if his Divinity world would be included into the Forgotten Realms?
Definitely not. Baldur’s Gate 3 has helped Larian grow their studio and get more exposure, but they very much want to own their own IP. It is the same reason BioWare made Dragon Age and Mass Effect instead of just continuing to make D&D and Star Wars games.
If the Divinity world was somehow folded into the FR then Larian would need to give up ownership and creative control.
