First, all new hires get a 401k type plan with employee matching, like large company private sector employees do.

Second, for all emloyees who are not vested (less than 5 yrs employed, I think, it might be 10) refund their pension contributions and put into a 401k and match it. (yes, the employees pay into the pension, it isn’t free to them.) Then 401k going forward.

As for the vested employees, leave them alone. They have a legal and contractual right to their plan because they are vested. This can’t be abolished on the state level because federal laws also apply.

Over time (decades) the retirees will die off and the pension obligation will go away.

Doing something like this will be HARD. We can’t just wish this problem away.