At some point it should become necessary to recognize and acknowledge that self-government has failed and must end. I'd suggest some form of a city death penalty - declare the city dead and give the locals a one-time offer of relocation assistance to an approved list of better places. The city government, and anyone who remains, are officially on their own.
We've known Flint (and many similar cities) are doomed for decades. Why do we keep them alive as zombies rather than just help the humans and let the municipalities die?