Probably not going to be hardware extension, because all the new stuff would have to travel via USB, it just slows everything down, like buying and feeding 10 cows, but you can only milk 2 or 3 forever, it would be so wasteful. HD will require more resource like RAM than the Wii have atm, all the anti-aliasing, textures etc on 3d games and the higher resolution will just need more VRAM and faster processor to play smoothly.
Go online with Internet Channel on the Wii and load any youtube video (http://www.youtube.com/xl/) , you'll notice the framerate is just terrible compared to watching it on your PC, sure youtube vids are flash based and the plugin used might not run the best on Wii, but thats just too far a margin from being good for even standard definition.







