I'd also like to see Nintendo branch out more in terms of collaborathing with outside studios; many great games from their past have resulted from such partnerships, such as Mario RPG with Square, F-Zero GX with Sega, Astral Chain with Platinum, Sin and Punishment with Treasure, Metroid Dread with Mercury Steam, etc.
I'd love to see, say, Diddy Kong Racing 2 by the old ex-Rare team at Playtonic.
Not only can this help bring a freshness to some of their IPs, but as games become more intensive to create, they're going to need to work with external partners to ensure a steady flow of software.