I think the larger EAD Tokyo group is already working on Mario Galaxy 3 (or whatever they want to call the next big 3D Mario game), but it's for the Fusion platform launch window, not Wii U.
Wii U has gotten or is getting NSMBU + Luigi U, Mario 3D World, Mario Maker, and possibly will get a Galaxy 1/2 HD Collection (Mario 64/Sunshine remakes too?), that's plenty of Mario for a system that is their lowest selling console.
There's no point in wasting another 3D Mario on Wii U, if you haven't bought one with NSMBU + NSLU, Mario Maker, Mario 3D World, Mario Kart 8, Smash Bros, Mario amiibos, possibly Mario Galaxy 1/2/Mario 64/Sunshine remakes (?) ... odds are you were never going to buy one any way for any type of Mario game.
The next Nintendo platform *must* have an incredible launch or their future in the game hardware business begins to look very poor indeed. They cannot repeat the 3DS and Wii U launches.







