If it really is an economic slump that's causing PS3 sales to be slower to adopt than usual, As soon as the economy is an economic turn-around, it should pick up speed isn't that right?
Personally, i don't think the Wii is winning because it's just so damn cool and fun, but rather that's all people can afford right now and it's the cheapest alternative to next-gen gaming.
This is probably why economists have said in the long-term, PS3 will come out on victor once HDTV's start selling again to replace outdated standard tv's. Even analog is on it's way out to make way for digital television.