The Wii U has already been announced to support backwards compatible with previous Wii games. Nintendo will go further to make available GameCube titles as digital downloads for their new console.
Amber McCollom, director of trend marketing at Nintendo America said:
You know it’s interesting that you bring up backwards compatibility and Nintendo’s history usually goes back one system. The Wii was compatible with GameCube and Wii U will be compatible with Wii and that’s pretty traditional in launches from Nintendo.
GameCube discs will not be compatible with Wii U, but a number of the games that were playable on GameCube can be downloaded from WiiWare.
The Wii U is expected to launch in 2012, next year.