The banks aren't going to do anything, and the state probably can't do anything. They're going to have to cut spending and raise taxes. The city should consider changing to a professional manager form of government that also would make the controller a civil-service position rather than an elected one. The city's options are limited. Officials can't raise taxes because the already-shrinking tax base would get smaller.
State aid is the only other option.
I believe it's the expenditure costs that cause the problem. Looking at revenue is not enough. We have to look at the expenditure side. This is not a problem unique to Pittsburgh. It's population changes, it's the number of people moving from the cities to the suburbs.