A three-league structure in AAA would require the presence of an 8th team based in either the Mountain or Pacific Time Zones - currently there are only 7 such teams due to Fresno being demoted.
I think the Dodgers could move their OKC club to Rancho Cucamonga as a promoted Quakes once each level of organized baseball, including the majors, expands to 32 teams. The partnership that currently owns OKC would purchase the Quakes. A new stadium would probably be needed for the promotion of the Quakes to AAA.
The Low-A Quakes could possibly move to Santa Barbara, which did have a Dodgers affiliate in the past, but currently lacks affiliated baseball.
The move of the OKC Dodgers to RC would open the door for the Memphis Redbirds to relocate to OKC and assume the history of the OKC Dodgers, while a new Memphis AAA team is launched as the top affiliate of the new MLB team in Nashville, but inherits the history of the Memphis Redbirds. Chances are the ownership of Nashville MLB will want to have their top affiliate in Memphis, so all of this needs to occur.