It may be just wishful thinking on my part, but I do not think that we are protecting Saudi Arabia. The minute we took control of Iraq (securing a stable oil supply for the world) the first thing we did was take our military out of Saudi Arabia.
I do not see us rushing in to help Saudi Arabia in anyway with their AQ problem. I think we are going to let them sink into civil war. The princes will either have to clear out AQ from the kingdom(something we have been asking them to do) or they will die at AQ's hands. No more status quo from us, and we do not have to lift a finger. Muslims can fight among themselves, keeping the war over there and not on our soil. Maybe they will exaust themselves.