And there are enough real-life instances of this segregation (gated communities etc) actually happening to make it all sounds rather plausible. But, in my modest opinion, such a situation is not actually "the best" the rich can hope for, even from a purely selfish point of view.
In this blog-post, I will try explain that belief to address a comment James made earlier: "Your views seem to differ from those of most left-wingers in that you view socialism as a vehicle for advancing middle-class interests. Clearly, you are not alone in this belief: I remember reading an article by a left-wing columnist (it might have been Robert Reich), in which he lamented the left’s failure to persuade the middle-classes that their interests would be best served by siding with the poor against the rich".