Ok I'll give it a try. I won't predict "total" lifetime sales, though. Instead these are my predictions for 2011-2012
Wii: 120-130 million
Why: The console is selling extremely well and it will continue to do so. What else is there to explain? 
Xbox360: 45-55 million units
Thanks to Natal I'm positive Microsoft will support the Xbox360 for some more years. Personally I doubt they'll go for heavy price drops as they'll want to concentrate on profit now so I'd say 50 million units till the end of 2011 sounds good.
PS3: 40-50 million units
Sorry but even if Sony has a "10 year plan" for the PS3 the PS3 is not going to sell 25 million additional units after its 6th year on the market. 50 million sounds like a good bet to me.
Great, now I spent 15 minutes of working time on this little post
Edit: In case Sony has really huge plans for the PS3 Slim and will push it like crazy an additional 5 million units sounds appropriate. That being said I doubt they will cut prices that fast (less profit).
