Very interesting observation.
I think within the city limits of Detroit the population is 85% black. If an ethnic city was ever going to work that should be the perfect proving grounds.
They control everything. Government, schools, police, business, housing, etc.
Crime is off high end of the scale, the graduation rate is something like 25%, unemployment around 30%, not sure about the welfare rate but 50% might be a good guess, and they have no tax base.
You guessed it...They blame the problems on whites leaving and taking all the good jobs with them.