Wii will seem even further behind graphically in 3 years.

I must disagree.  Will X360 and PS3 games look even more impressive than they do today?  Of course.  But look at the most popular Wii launch games worldwide: Wii Sports and Wii Play are about as graphically simple as you can get, and Twilight Princess is a GameCube game with a 16:9 mode as its only notable graphical addition.  Clearly with the improvements made over GameCube Wii is capable of a lot more, so I think the Wii games of 3 years from now will seem at least as improved as the X360 and PS3 games.  If the graphical difference now isn't already a deal-breaker, I don't see the situation getting worse.