With USC & UCLA joining in 2024, giving B1G 16, I think the next phase will add Colorado, Utah, Kansas and Pittsburgh.
All AAU
Pitt helps the east coast and restores a PSU rivalry. They solid enough in football and hoops. Also fitting in nicely with Maryland, Rutgers, and anybody else they get scheduled against in league.
KU is basketball mecca (Big Ten would love them) but they are kind of turning things around in football. Plus playing Huskers or Iowa or Northwestern or Minnesota or Wisconsin or Illinois - just fits in nicely.
Utah (football and hoops) Mountain West and Colorado (Prime) add flavor to USC and UCLA.
Just been my hunch since the moment we heard USC & UCLA going to B1G because that makes sense to me (and not TV market sense since I could care less about TV dollars - the conference already banks more than enough)
Oregon and Washington are way too far for east coast games, and they seem to have little brothers (Oregon State & Wazzu State).