The first proper entry in Nintendo's The Legend of Zelda series for Wii U will have an open world to explore, but perhaps not in the way that you're expecting.
Modern open-world games like The Elder Scrolls V: Skyrim and Grand Theft Auto V aren't indicative of what we'll be seeing from the next Zelda, franchise lead Eiji Aonuma explained in an interview with EDGE (via NeoGAF). "Since we’re talking about open worlds, let’s state upfront that we don’t plan to have an open world in the same way other companies have been doing in recent years," he told the outlet.
Perhaps we'll see an open world more akin to the original The Legend of Zelda or even the recent 3DS title A Link Between Worlds. I guess we'll just have to patiently wait for Nintendo to drip feed us more details. In the meantime, let us know what kind of open world you'd like to see in Zelda Wii U.