While I can't truly say, my belief is that it won't be as easy or even as possible as people think it will be. Based on my understanding (granted, it's not a whole lot, I'm more 3/DS-oriented), the reason why Nintendont works well under Wii mode and on a Wii itself is because of how close the Wii environment matches with the GC. Remember, the Wii U utilizes actual Wii hardware under the hood to run Wii mode, and that hardware is set to Wii specifications. The Wii U hardware like the GPU are quite different. In all honesty, if the Wii U hardware were just an advancement to the Wii hardware and Wii games ran off of that, then having the separate Wii hardware would be quite redundant, and Wii mode would have already been able to do things such as 1080p without a hitch by Nintendo.