"Is it possible Duke will become, effectively, a black college?"

IMO, No, it is a terribly expensive place to go, attend, and receive a degree in political correctness.

Durham is a scaled-down version of New York City, Washington, or San Francisco. A ruling hard-core liberal political base trying to pretend they care, while placating a substantial minority population.

Only a matter of time time before the two tigers look each other in the eye.

You have a corresponding situation here; how many times did they ignore the happenings at North Carolina Central University, then go after those rich white students to curry political favor with a substantial bloc of the Durham voters. This local government and enforcement of its laws, was very selective. Not as a matter of ensuring public safety, but as a matter of political correctness.
I have relatives in the area, and my son also graduated from UNC at Chapel Hill,(just a rock's throw away, but if you ducked, you would not get hit) he rarely ventured into the Durham County while attending, the locale was known as a third-rate speed trap and money-grubbing citations generator.

Duke University, in conjunction with the local Gestapo allowed the situation to persist for years.

The local government officials and the Duke University administration should be held accountable and examine themselves to see if they have enough personal integrity and citizen support to at least be honest.