I think that if the third-parties shifted their main work to the Wii, then it would be the beginning of the second great games crash because people that enjoy the hd games in all their glory won't suddenly shift to a console that can't produce those types of games that well.
Sure, Nintendo has gotten some excellent sales on some titles, but the sales for Wii Sports can be explained by saying it has only sold so many copies because it is packaged with the Wii. Wii Fit has sold as much as it has because of the ringing endorsements it has received from non gamer sources and from pr generated for the game because of youtube videos featuring skimpily clad young women using it.
But Nintendo hasn't really shown that they can make new games that will appeal to all gamers and games like Mario Galaxy and Zelda: Twilight Princess really haven't attracted many purchases from Nintendo's "New casual group of gamers." Not everyone that has Wii Sports has opted to get the best game on the system which is Mario Galaxy.
Heavens to Murgatoids.
