I understand. Contracts are binding and are generally held to be sacrosanct. The money IS owed, but if the money is simply not there to make those payments . . . I do not know what the legal precedence is or what the implications are for public agencies to declare some form of bankruptcy. Far fetched perhaps, but we live in rapidly changing and unpredictable times. 
And I don't know if some of the financial pressure on PERS and public agency obligations to finance the system would be partly mitigated if we got into a period of rising inflation and interest rates.