Nintendo has already confirmed that WiiU will eventually support a two-Gamepad experience. I hope that when they do show that new 1st party game that requires two Gamepads (E3 perhaps) that they plan to bundle it with the controller, hopefully for $99 by then.
That way it will be similar to WiiFit in that consumers felt like they were spending $90 for the "WiiFit experience" rather than just a pricey peripheral.
I think they said the wii u would support two gamepads because people flipped out about it when they initially said it would support only one, but that's a ton of stress on a system having to steam to two controllers. No way it would work with a Call of Duty BO2 for example, the way it does with one controller.