I don't know how good the game is going to be...
If it's well reviewed, I reckon it will sell at least 750k, and probably more than a million. It is much more mainstream than for example Madworld which sold 400k already.
I think Ubisoft is being overly cautious with their prediction. I just hope that they don't make it a self-fulfilling prophecy by not convincing retailers to take in copies of the game, or severely reducing advertising or something like that.
My Mario Kart Wii friend code: 2707-1866-0957