It's probably not possible with the current WiiU though. I assume the compression and transmission happens on a hardware level. A revision of the WiiU with h.265 streaming or beefed up wifi could do it. It would be nicer if they could first extend the range.
The Gamepad goes through the 5GHz wifi band due to its higher bandwidth and less interference but it's limited by range. The 2.4GHz band has the range advantage but the other are CONS.
I think the Gamepad uses miracast.. wifi-direct, but not really sure.