yeah that's just not gonna happen. PS3 last year hit 88k, year before 108k, year before that 50k.
Even the wii hit 158k this year. Only in the biggest year ever for a console in 2008 the wii didn't go below 210k, you think the ps3 can sell like that?
As far as 360 goes it will probably go below 120k, but it has nothing to do with Natal, going below 120k isn't even bad. As you can see PS3 hasn't been able to do that yet either.
currently playing: Skyward Sword, Mario Sunshine, Xenoblade Chronicles X