With Microsoft buying RPGs studios one after another when is Larian’s turn? Imagine it, Obsidian making a Fallout game in Divinity Engine

Not gonna happen. Larian's previous experience of using a publisher was not a happy one so they'll be remaining independent...
Go with CDPR, its new publisher on the rise for sure. Next 10+ year is gonna be huge for CDPR. Witcher 4 and Cyberpunk 2 turns them into greatness, imho. Thats if they keep doing things like they have.