Cav will be fine in the Mountains - he has slimmed down specifically to help his climbing (with a slight lack of speed though.)
He was even joking the other day about pacing Bernie Eisel up the hills.

The only thing that will prevent him getting to Paris is London. There is only a week or so between the end of the tour and the Olympic road race. If he feels tired in the Pyranees, he may well drop out. That said, the lure of a stage win on the champs elysee is mighhty strong to a sprinter, so who knows.