People just seem to think that the botton is going to magically drop out for Wii sales, like everyone on earth is going to decide to stop buying a Wii at the same time. Consoles that are strong enough to clear 100 million units will obviously have very strong legs as well..
As was mentioned here I believe, many of PS2's sales came AFTER its peak year. A large chunk of its success was its legs; its endurance. Which is what Wii should have as well, and there is really no reason to believe otherwise, unless Nintendo should prematurely cut its life by releasing a new console too soon, which would be a foolish move. But even then, the Wii would still sell just like PS2 did after PS3's launch.
People point to the fact that the Wii has seemed to have past its peak relatively early, but that really means little in the grand scheme of things. What really counts is the endurance of the console. If it passes its peak in year 3 but goes on to have 2 more years of 15 plus million consoles sold (average) and another 3 years of 10 plus million consoles sold, just like that you've added another 60 million and the peak no longer really matters.
