I think it will be a close call this year. I did not get into guessing how many consoles GTA4 would move. I just stuck with a solid AVERAGE... the summer months will be much lower than this week, but I used this week.
End of 2009 Predictions (Set, January 1st 2009)
Wii- 72 million 3rd Year Peak, better slate of releases
360- 37 million Should trend down slightly after 3rd year peak
PS3- 29 million Sales should pick up next year, 3rd year peak and price cut