re: Has Affirmative Action caused HBCUs to crumble?

Yes and no. Affirmative action and quotas are a part of it but much of it the increased non-legislated opennesses we've seen in recent years.

It used to be that average or good black students attended HBCUs because they couldn't attend anywhere else and then with integration and AA many still chose HBCUs because they were easier to pay for or they felt more comfortable/welcomed.

Now with society more open than ever and with more scholarship/financing opportunities the very bottom of the barrel are choosing HBCUs while the rest are attending better and more integrated schools.