This is reality and no amount of whining about fairness or past promises will change it.
Bankruptcy laws should not allow a private entity to go through bankruptcy and continue to operate while discharging its debts. The same should apply to public entities as well. That they may currently allow this is something we need to fix.
If we cannot ensure debts to be met under law, then we should forbid the debts from existing to begin with.
While municipal corporations can dissolve, that wouldn't solve anything. County and state governments can't afford to pick up pension obligations on behalf of cities. And we'll probably find that some entire states such as Illinois can't pay their pensions. There's no way for a whole state to simply stop existing.
These people have already sold their services for a promised benefit which is now not being given to them. If there is bankruptcy it should come at extreme costs to the extent that the voters in the location feel pain equal to those who are having their pensions cut. Clawbacks, criminal convictions, liquidations, ensuring that the pain is not felt just by those who are having their benefits stolen and given to someone else.