“Could it be said to be punishment if the person being punished does not exist?”

One line of thinking is that there is a period of actual punishment, depending on the individuals severity of sin, that is limited (some shorter, some longer) in time, then annihilation for eternity. Kind of like Sodom and Gomorrah, where the inhabitants undoubtedly experience pain for a limited duration, then annihilated.
Geomic