That's not happening in the mid-term, and probably never due to NIMBY. But after the Navy handed it over to the Marines, they invested billions in infrastructure. It was in play maybe during BRAC and actually would have been a great opportunity for San Diego county in many respects. At the very least they should have turned the south side into civilian dual-use, but that ship has also sailed due to housing developments, noise and NIMBY.

Also the Marines like having some QOL for their personnel and dependents when off duty, so while they could in theory move to the desert, they're not necessarily falling all over themselves to do so.