I can't wait to see what they come up with. Super Mario 64 is still my personal favourite 3D Mario game, so I'm personally wishing that it'll be more like that. In fact, I made a post about what I'd like to see in a new 3D Mario game, which I'll re-post here if you don't mind:
MartinIsAwesome wrote:I can see a lot of potential for a platforamer that switches the action between the TV and the GamePad screen.
Taking the example of Mario game where going down a pipe on the TV takes you to an Underground stage that plays out on the GamePad.
Alternatively, imagine a game where at first, nothing (or something very basic) is shown on the TV screen and you play the game on the GamePad in a Hub World, like Peach's Castle in SM64 for example. Then, only when you jump into a portal to gain access to level (like the paintings) all the action switches to the TV where this giant world unfolds. That would be a rather magical moment.