It totally depends on national will. If the public is strictly against US presence, and the leadership follows suit, do you think US will put its forces under danger in tiny based surrounded by hostile public and hostile military in a foreign land? Ofcourse not. Unless they want to fight a war there and US doesn't have the stomach for it.
US allies are advanced and industrialized to the point that if they want they can easily kick out US forces and also switch sides to China. The biggest problem is mental subservience that has been taught to them for generations.
Have American left Iraq yet?
