The Wii will outedge the X360 this Christmas. Just barely though.
Wii's (bigger) supply, since they'll have a lot + Mario Galaxy = Guaranteed sell outs for the Wii. If I'm to believe Reggie they'll do at least twice as well as last Christmas since they have twice the supply.
The X360 needs to maintain its current momentum to stay neck and neck with the Wii. Luckily it has several recent highly-ranked and big sales games (Bioshock, Halo 3 etc.) It also has the Arcade Bundle, which is an excellent casual Wii clone. Clerks are going to say "Yeah we're sold out on Wiis, but for ONLY $30 bucks more...") So every unsupplied Wii becomes a X360.
Once the year is over though that's it. Nintendo's supplies will be at plenty while the Christmas buzz for the 360 wears off.
Then Smash Brothers Brawl comes out.
There is no such thing as a console war. This is the first step to game design.
