So you believe like the demoweenies that if we leave there are no consequences?
For us?
There will be adverse consequences no matter what we do. We're in a bad situation and there's very little we can do to make it better. The only silver lining in all this is that it showed the stupidity of the neocon plan of democratizing the Middle East. Hopefully we won't engage in another fool's errand like that again.
As to whether we should leave, I don't know enough to say. I'm inclined to that position, but I am not certain of it. Obviously, there will be bad consequences to leaving, but I have yet to see anyone make a reasoned argument as to why we are any better of staying.
With my limited knowledge, it seems to me that withdrawal would result in a full blown Sunni-Shia civil war, with possibly Iran and Saudi Arabia getting involved. I don't see why leaving your enemies to fight each other is such a bad thing. Of course, withdrawal would have other bad consequences, such as a loss of prestige and a propaganda victory for the Jihadists, but it seems to me that staying can only postpone it.