In the U.S., when I look at a room with hotshot businessmen in 2014, I know that the 2024 one will be different (except for businessess subject to bailouts). The same cannot be said in Europe or in places where the state is powerful. And if I look at the bureaucratic and academic establishments, the only people who would drop out of the 2014 cohort are the retired/deceased ones.
Static measurements of inequality are defective (in addition to their traditional lack of mathematical rigor). True equality in income is probabilistic: it requires downward mobility. This should map to opportunity. I quickly wrote down the sketch of what such a true measurement of equality would be like.

https://docs.google.com/file/d/0B8nhAlfIk3QIX3AzcHFkaGtORkU/edit