He does have a point, most recent studies show that social mobility has been decreasing in the United States. Whereas the US used to lead Europe, Europe now lead the US. Also real wage increases has been very disproportionate in terms of the rich gaining and the middle class/lower class standing still. This will result sooner or later in a stratified society.
As for social mobility in China? I believe it is still very high, on the merit of there being no such thing as old money, and the fact that in an aggressively growing economy, one good idea can still easily launch you into the "landed class".