Your on to something, but even just requiring government workers to hit the a retirement age of say 65 before they can collect their retirement or to offer reduced benefits to those who would like to collect them early could be quite substantial. Of course that is the draw to government work to work for reduced salaries now, for good benefits later. Might require an increase in wages for current workers.
A good honest look at all the services we privatize could save billions of dollars too. We do not necessarily save money doing that every time.