It's a bad sign for a city if it goes bankrupt. Cities should try to improve their economies so that they can be profitable. Rather than giving up and declaring bankrupcy, cities should try to find a realistic solution. No one will want to invest in a city that has failed in the past.
Why would we need more cities to go bankrupt? This is an absurd idea. We should be focusing on getting the cities close to bankruptcy back on their feet and back into having a stable economy and not allowing them to go bankrupt. We need to focus on repair not just allowing them to go downhill.