I don't see a cut that's acceptable to all parties though. Nintendo provides very little to xbox in that situation while xbox provides direct competition to nintendo's marketplace
I really don't think they would, though. Not any more than any other third party software is competition for Nintendo.
Let's remove the console wars angle from it. Let's say Ubisoft was really interested in increasing their subscription revenue (they are), and they said to Nintendo that they would keep making Just Dance games for Switch and even start bringing over Assassin's Creed and Far Cry games, but only if they could be made available as part of a multi-game Ubisoft+ subscription, because that's what they're trying to move their customers towards. They would still be available on the eShop for purchase, but users would also have the ability to purchase a subscription through the eShop that would give them access to all the Ubisoft games. Either way, Nintendo would get a cut – a cut of the purchase price if someone buys the game, and a cut of the recurring subscription revenue of someone chooses to get "Ubisoft+ for Nintendo Switch."
Is that Ubisoft opening up a competing marketplace to Nintendo? Not really. That's basically what I think Game Pass on Switch would look like. It would just be Microsoft's version of a subscription service that provided access to all of their Switch games.
I think subscriptions in the eShop are inevitable. Basically every major publisher that isn't Nintendo sees that as the way things are going and wants that to be the preferred way to get their games. Ubisoft has even started tacking "A Ubisoft Original" into the logos of all of their games, as if they're a streaming TV service.
All of these companies are going to want Nintendo to support subscriptions, and I don't think Nintendo is likely to resist because the reason all these companies like subscriptions is because they're reliable recurring revenue, and that means reliable recurring revenue for Nintendo as well.