The same thing that happened after their retreat from Vietnam. They will be gone, which will be a damn good thing...and the country they wrecked for no good reason at all will slowly reshuffle itself into some kind of new status quo (if it doesn't fall apart into 3 pieces), and that will be tough on a lot of people there until it sorts itself out. In Iraq, it will be very tough on the Sunnis in particular, and probably pretty tough on the Kurds and Shiites too, but that is unavoidable at this point.

Meanwhile, Americans will continue to speculate as to when the new Playstation or Nintendo comes out, who will win American Idol this time, and other such total BS, and life will go on.

You're living in the latter days of the Roman Empire, my friend, you just haven't realized it yet.