I believe that Wii U is better off with a Radeon HD 6870 GPU, because it needs 2 GB of GDDR5. I'm getting a Radeon HD 6970 for my birthday and the Wii U needs to keep up. This can do 75 frames per second instead of 36 frames per second on the HD 4800. The Radeon HD 6970 is a little worst than my Radeon HD 5970 Black Edition in terms of frames per second, but it has better power consumption. My Radeon HD 5970 cannot do openGL 4.2 for example. Radeon HD 5970 can only do openGL 3.2, but it does do DirectX 11. Radeon HD 6970 can do DirectX 11.1 however for even prettier graphics. Wii U is supposed to last 6 more years
I wouldn't mind the Wii U going up $70, because of the Radeon HD 6870 inside. $60 games is normal these days.