In an interview with Famitsu, translated by the good folks at Polygon, Shigeru Miyamoto hinted at a new franchise coming to Wii U in 2014.

With the recent version upgrade [of the Wii U], we've worked on the system side of things and we're planning on further system tweaks ahead, but even as is, [the Wii U] has become a useful item for the living room. However, it's pointless to talk about other features, no matter how fulfilling, without releasing games of our own, so we hope you'll look forward to the games to come. Next Spring, with the release of Mario Kart 8, we'll have a general selection available, so I've been thinking it would be a good time to bring out a new franchise.

Miyamoto did not disclose much, but did say this new franchise has kept him quite busy at work.

I can't say too much in detail right now, but I've been pretty busy with this title these days.

If this new franchise comes to fruition it will be the first new Nintendo franchise released on the Wii U since the launch title Nintendo Land.