A lot of people expected Retro Studios to be working on Zelda for the Wii U, but this is not the case. Shigeru Miyamoto has confirmed that while the idea of them working on a Zelda title is “not out of the question”:
…they’re too busy for that sort of thing right now. It would probably require me to be involved to a great extent as well, so I would have to get over quite a bit too.
Of course, he “can’t say exactly what it is that they’re very busy [working] on”. And so we continue to play the waiting game. But that said, if it’s not a Zelda title they’re working on, what do you think it is?