And millions will be slaughtered.
There is no reason to believe that wouldn't be the case -- the only question is who would be slaughtered by whom, and how long it could continue before the entire region hemmorrages to the point that talk of returning begins.
In Mona Charen's excellent book Useful Idiots she outlined how New York Times writer Sidney Schanberg rose to international fame as the reporter who told the world about Pol Pot's "Killing Fields." Sam Waterston of Law & Order played Schanberg in a movie that won an Academy Award for Best Supporting Actor (the late Dr. Haing S. Ngor). What most of the world has forgotten is that when the U.S. was still in Southeast Asia, Schanberg was foursquare for the pullout, quoted as saying "[N]othing could be worse for the Cambodian people than the American presence."
(Ann's got the looks and the publicity, but Mona's got the writing skills, and NO, I'm not apologizing for saying that.)