I think Nintendo will have games on Gamepass and X Cloud. Not the big Switch games, but the Nes, Snes, N64, GC and Wii games.
I would say its doubtful. Never say never, but you're confusing the motives of each party here. MS is doing this to win the streaming wars/battle for the cloud.
Nintendo's reality is they are just a game company and for their business model to have any value they need to keep their core IP on their core platform. Otherwise their business model doesn't really work.