I'm not exactly sure what the GP was talking about, but if the pension benefits are guaranteed and greater than the return on funds invested in the pension, then the only way the pension plan could be sustainable would be in some growth scenarios. In many growth scenarios, though, it wouldn't be.

This a problem with many public sector pension plans. Many cities across this country have pension plans that guarantee pensioners income that cannot be paid from the plan without screwing over future retirees.

Clearly this issue has to be evaluated system by system.