They are always aiming in selling their Toys, from a simple business perspective and they would still be selling. Why any Mainstream Nintendo Gamer would buy another machine to Play Stadia + Nintendo?
That move would at least give them legs to go the hardware route, until going full Third-Party.
Perhaps. Though even if they didnt allow it Nintendo gamers could just use Stadia on their phones. not as ideal, but its not like the option doesnt exist