This violates the Constitutional right to Freedom of Association[1]. Corporations will sue, it will go to the Supreme Court and get struck down. Would an all-female board be forced to have a male? Would an all-Jewish board be forced to have a non-Jew?
Hopefully the companies will find quality board members for these slots and not resort to the fake executives that were popular a decade ago on Chinese company boards of directors. https://www.cnbc.com/id/37759560
[1] https://constitution.congress.gov/browse/essay/amdt1_2_13_1/....