I'd like to make a quick comment on this stuff. I own ~15 consoles including all of the current generation ones, and at first I thought I'd buy all the next-gen ones too. But after I add up the system cost, controllers, accessories games and tax, that's more money than I really SHOULD be spending, even if I can. I have enough current generation games to tide me over until there's some killer next-gen games. I don't want to buy something just because it's new and then wait years for the good games to come out. If I do get something on launch, it'll be Wii, because the launch titles, innovation and the price (hopefully XD) are most appealing to me, personally. ^^
About price affecting sales: to what extent, we'll have to see, but it certainly will be affected. Below I link two GameFaqs.com polls. Regardless of what people think of the message boards users there, the site itself is visited by a wide variety of gamers, and with a fair amount of accuracy we can see the opinons of the average gamer on these issues. The first poll is
excellent, in that it isn't console specific and therefore isn't subject to fanboyism. 70% of the voters purchase fewer games because of prices or no new games out that they want. While price was dicussed already in great length here, it's also important to note that these consoles are just a means to play the games, and the games themselves are what's important. I think those two factors, price and software will be the strongest determining factors in how well these systems will sell.
http://www.gamefaqs.com/poll/index.html?poll=2378
http://www.gamefaqs.com/poll/index.html?poll=2379