The elite looks different today, but no, it is not really so different than when C. Wright Mills wrote.
Demise of the old power elite, rise of 'overclass'
According to commentators, the higher circles in the US has indeed become multicultural.
The Great American Celebration
The New Deal and WWII had forever transformed the corporate based power structure of the earlier decades.
The Power Elite
Almost all the members of power elite were white Christian males, coming from upper third of income and occupational pyramids.
Connection between golf and business
Golf allowed males to play together, shoot the breeze, and do business, creating a sort of corporate culture that allowed them to become comfortable with each other men similar to themselves.
Difficulty in 'fitting in'
Whether or not playing golf is necessary to fit in, women who make it into the coprorate elite must assimilate sufficiently into the predominantly male culture to make it into the comfort zone of their male elite counterparts.
Thesis
The power elite has been strengthened because diversity has been achieved primarily by the selection of women and minorities who share the prevailing perspectives and the values of those already in power.