I don't know about crush. Obama is clearly the better orator, is more articulate, and generally has a better command of the facts.
However, we can't forget the Kennedy v. Nixon debate. Those who listened on the radio thought Nixon won. Those who watched it on the tube thought Kennedy won. Nobody listens anymore; everybody watches.
And what they will see will be a kindly looking old white guy with a more folksy manner of speaking sparring with a...well, a black guy. I don't think anything Obama could possibly say will sway those who only care about his complexion, and those people are far more numerous than they will admit.
So, no, Obama will probably not crush McCain, simply because in the eyes of far too many, McCain can't lose to a non-white. Obama may "win", but the margins won't be as great as they should be.