As far as I know, Stephen King loves working with people creating something based on his novels. So The Dark Tower game could be the really neat possibility.As to taking on Martin (yuck!) or Tolkien, I think and hope the answer is an unambiguous and immediate no.
These are IP that would be fantastically costly to license, with creators that are unprofessional (Martin) or suffer from author existence failure (Tolkien).
As they have done with Cyberpunk 2077, they should instead choose:
* Works that are part of the cultural heritage of their core market (as The Witcher)
* Works that they themselves enjoy and can establish a solid foundation with the author (as Cyberpunk)