Wii is losing third party support as fast as a crashing plane is losing height. For 2011, there are only 2 third party games listed : Driver San Francisco and Ghost Recon Future Soldier. Those games will sell a lot more on HD systems so there's no chance they will lift Wii sales. With no games coming Wii hardware sales will only slow down as Kinect/Move appeal to people that have no system yet. Existing users surely buy whatever games Nintendo has to offer but hardware sales won't return 2008-2009 levels without outstanding exclusives.
As for Nintendo releasing Wii2, that certainly won't be a simple matter. Nintendo faces defiance from core gamers disappointed buy the orientation taken by Wii/DS software, so this audience is not likely to buy Wii2 without a rock solid line-up (which Nintendo can't have without third parties), especially if good games keep releasing on PS3/X360. Wii owners probably won't buy the system at once because it's bound to be expensive (at least if Nintendo puts the technology to compete with PS3/X360), and casual gamers (i.e. people who spend little time playing and don't consider video games as their primary leisure) won't see the necessity to upgrade especially with Wii is their first system.
Therefore whenever it releases, Wii2 probably won't see many early adopters unless it comes with something revolutionnary (like motion control was for Wii)
