Don't be so quick to throw out affirmative action.

I don't think the whole of the problem of women almost entirely absent in positions of power is "women underperform due to internalized sexism", a significant slice of it is also "affirmative action" by the sexists, passing women over for promotion, disrespecting and devaluing their contribution. If you remove one thumb from the scales, consider that the other thumb might still be pushing them out of true. (This simple consideration is, alas, lost on the current USA supreme court.)