The Wii will be a bit top heavy in the Plat categotry, it will have 5-6 games(conservatively... WiiPlay, WiiFit, MKWii, SSBB, WiiSport, SMG...) sell 10 million plus, while right now Halo 3 on the 360 looks to be the only game with a shot. (maybe GTA5.... but we'll see)
as far as total million sellers it will be close between the Wii and 360... mainly becasuse the 360 will have a large % of games in the plat cat that sell bewtween 1-2.5 million.
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