A "Larian-style game" wouldn't be exactly easy/cheap to make either, eh?
I think what could be incredible, but unlikey, is to make a series of LotR-games that add onto each other. Basically WB would announce a "Lord of the Rings: The Shire"-game, then next year "Lord of the Rings: Rivendell", then the year after "Lord of the Rings: Rohan", and so on. The "twist" would be that you can stack each new game onto the previous, so the ingame-world seamlessly grows bigger as WB adds more games. So, focus on one area for maximum details, but still a vast world over time. Will never happen, but one can dream ;>
Hogwarts Legacy isn't like "most open world games", that's the point.