The tease in the latest issue didn't really hint about what the game could be, though it did tell us what it isn't. It's not Star Fox or F-Zero:
"OOOOOH! New Wii U game! (And no, it isn't F-Zero or Star Fox)."
Whether this means we're looking at a brand new franchise/IP, or if Nintendo is dipping into some other part of its back catalogue of characters and stories - perhaps another Metroid title? - we don't know, but we know it isn't Sonic, as the hedgehog's new game (and TV show) Sonic Boom was announced last week.
What do you guys think the new Nintendo game could be?
If it isn't a new IP, it will surely be a big name in the Nintendo character roster, as the company knows at this point that its console doesn't have the install base to support weaker characters. Maybe it's Kirby? Or Wario?