Nintendo are gonna have to do a lot to make their NX exclusive games look worth buying the console for. If they push out NSMBU type stuff, people will not be able to discern the difference between that and their $60 titles and say "what's the point?"
Even games like DKC Tropical Freeze and Yoshi's Woolly World, as much as I love those games and 2D platformers in general, if Nintendo don't get aggressive with making their franchise look AAA material, they will fade into obscurity.
Unless they go third party and exclusively make Mario, Zelda, Smash, and Pokémon games that is. Not gonna happen though.