In general, what I'd like to see from Nintendo on the Switch would be continued diversification of its library as well as the largest amount of Nintendo iOS available. I'd like to see Nintendo focus on franchises that haven't released on Switch yet that could bring new life to the series and to the Switch. I'd like to see new entries in Wave Race, Pilot Wings, Star Fox, Kid Icarus, Murasame, Super Mario Strikers, F-Zero, Wii Sports, Nintendoland, Nintendogs, 2D Wario, 3D DK, and Diddy Kong Racing. I think franchises like Pikmin, Metroid, Rhythm Heaven, Paper Mario, Wario Ware and Tomodachi Collection will have entries on Switch.
I think there is a decent audience Nintendo could build on Switch for more arcade and minigame style sports, racers and shooters such as Switch Sports, Pilot Wings, Star Fox, Wave Race, 1080, Excitebike, F-Zero, Super Mario Strikers and Kid Icarus. All of these games would be up Namco's alley.
DK always seems to be acknowledged by Nintendo as one of its biggest franchises with western Nintendo fans slightly favoring it more with DKC series, DK64, and Diddy Kong Racing. They sell very well and offer a different flavor than the Mario offerings. It is a pipe dream but I'd love to see a new 3d DK and Diddy Kong Racing on Switch. Given the newly formed Mario Platformer development team umbrella between EAD Tokyo, 2D Mario team, NST and 1UP. Perhaps they could release a new DK title. Since 2009 we have had:
2009-NSMB Wii
2010-SMG2
2011-3D Land
2012- NSMB 2 & NSMBU
2013- NSLU & SM3DW
2014- Captain Toad
2015- SMM
2016- SMM 3DS
2017- Odyssey
2018- Captain Toad: Treasure Tracker
2019- NSMBU DX & SMM2