I think we have had enough leaks to all but confirm that the next Nintendo system will look like the Switch except slightly larger and the controller attachment will involve magnets in some way.
What I am interested in is the software. The Switch did not have the whimsy apps that previous systems had. I still carry forward Miis from my Wii as a guest book of friends and family I played with. I loved StreetPass Plaza; I would take my 3DS on the subway with me every day and get random passerbys as NPCs in my games. The Switch doesn't have any built in software that sparks joy like that, since I imagine, the system was rushed to fill in the Wii U void and developers were busy getting the handheld/dock mode working.