There's a rich line-up of Wii U classics that Nintendo can steadily release over the course of the Switch's life. Appropriately mixed with brand new titles, I think these ports should act as a compliment to brand new titles. The second year of the Switch has been a little disappointing, but I can't really grumble too much, I'm still playing Breath of The Wild, Mario Odyssey, Stardew Valley and need to find the hours to step into Xenoblade's world as well. What interests me most is how Nintendo will leverage their big licenses in the next couple of years. With Breath of The Wild, there's potential for an amazing sequel which iterates on the some of the more nascent and opaque ideas. The console is an indie darling and third party support is slowly building up. There's so much potential here for Nintendo, but to carry a console on your back to its December years, requires forward planning, luck and a little help from the odd unprecedented relationship here and there. The Wii U proved they can't do it alone. Year 3 for the Switch will be very interesting indeed.
As for Super Mario Bros. U, it's a series which has never captured my imagination, failing to shine bright enough to emerge out of the shadow of Super Mario World, which, to my mind, is the finest traditional 2D platformer I've ever played. The series is a bad cover version of a classic song, without the soul and spirit of the original.