Don't get your hopes up. That is really not going to happen.
Why not? The only people it would strongly offend are the base, the religious right. McCain doesn't need them to win, but he needs independents and he's alienating the fuck out of them right now.
He's not alienating as many people that you would think. It's not going to happen because firing your VP is political suicide. He chose her for a reason, because he wanted to stir up the election. He needed to get his name back in the limelight after the DNC, and in that respect, it's working.