Probably right. Wii lacks the hardware power for a good 5/6 year life cycle.
I don't see how hardware power has anything to do with how long a console lasts ...
The difference in quality of graphics and processing power between the N64 and Playstation was huge but the playstation continued to sell (and have Million selling games) years after the N64 was discontinued; following up on that the XBox and Gamecube both had processing power advantages over the PS2 yet had much shorter lifespans.
Certainly, the difference in processing power between the Wii and PS3/XBox 360 is very large but so is the price difference. Eventually (say 2009/2010) the Wii will probably be $99 (with Wii Sports) While Microsoft is still trying to sell the XBox 360 for $200 (or more) and the PS3 is $300 (or more); there are far more people in the world who are willing to spend $99 on a console than are willing to spend $299 on a console.