ps3 will have trouble selling as well as the ps2 based purely on price point imo. not everyone can justify spending $500+ on a gaming console. right now it sells out easily because of low quantities.
it's also going to take ps3 a while to drop in price. right now they're losing around $200 per console, so even when the cost of manufacturing comes down, it'll be probably at least a year later, and even then they might be only breaking even. once they do drop manufacturing below retail cost, what's to say they'll even want to lower the price. that profit may be necessary to recoup losses.
wii is a good strategy. it's fun enough that it will, and already is, attracting non-gamers. gamers themselves will buy it because it is a good console and will have good games (like zelda). nintendo fans are all over it. it's also a good alternative to the more expensive consoles. you want a gaming console to play, aren't diehard loyal, shit $250 sounds a lot better than $400 $500 or $600.