Maybe

When the Wii U was unveiled at E3 2011, we only saw it working with one touch screen controller, but according to an anonymous source speaking to Develop Nintendo is beavering away on supporting a second controller.

Citing a "trusted game development executive", Develop says the Wii U codebase indicates that Nintendo is preparing the machine to support a second controller, though there are no such indications it'll grow further.

Straight after E3, Nintendo EAD designer Katsuya Eguchi said Wii U games using two controllers were being considered, so it makes sense that Nintendo is looking to add dual controller support for the machine, really.

[source develop-online.net]