Not interested in a 3rd Galaxy title (the first two were perfect as is, no need to milk it), but i'd like them to move back towards that style of play. As Slade said, 3D World felt more like 2.5D world. The title suggested more expansive areas than it provided. That suggested theme is what i'd like to see next (would also pose an interesting challenge. The larger the areas, the more creatively the platforming/puzzles would need to be integrated to stop the game world feeling like a cluttered mess).

Wii U - Spring 2016

super mario 3D galaxy! (is not my idea, i hear from someone in this forum, and i liked it)

all gravity mechanics, some 2.5D stages with gravity mechanics but with more camera freedom.
local multiplayer, huge world, new creative power ups, yoshi, .
the natural evolution, land-> world-> galaxy.
the next after that is super mario 3D universe

As they said, they don't know. My opinion is that it will end up a Wii U/4DS joint platform game. The other option is that it gets moved to the next home console if it comes earlier than planned. I think they just working on the game though, and when it's done it will launch for whatever system it suits best at that time.

http://gamerant.com/super-mario-galaxy-3-details-shigeru-miyamoto/

It could happen according to Miyamoto

I hope not. I want a brand new adventure that's fresh.

It will be for the Wii U but not a sequel to Galaxy, I believe it to be a whole new series without flag poles.

i hope its not mario galaxy 3.
i wanna see mario 64 esque game
its been too long without one.

Next console launch. Probably a 64 styled game

I would love the next Mario game to be open-world like 64! I would give Nintendo all my damn money!