As I assume the USC/Notre Dame rivalry will continue. I can’t see USC taking on an 11th P5 team team every year. The Trojans will welcome Fresno or SJSU and pay a MAC team to come into town. If they do play an 11th P5 team, it’d be against Stanford or a Labor Day neutral-field game against Texas or Bama.
So this leaves UCLA’s three OOC games. There might be pressure to schedule Cal for the next few years if they schedule any PAC X teams. Then surely they’d want to schedule in a win or two against G5 or FCS schools. If they do take on a 10th or 11th P5 team, there’d be a lot of national interest from Big XII and ACC teams, as well.
At least with BYU, they could call and have almost a guaranteed schedule opening within the next few years. I think BYU was reasonably willing to schedule as many PAC 12 teams that they could. But I don’t think they’ll find USC or UCLA as willing or as easy to schedule as BYU.