Pac12 football would be fine without UCLA, they have a big and engaged alumni base but aren't a national presence like USC and have sucked for a long time. USC would be harder, and it's untenable for the Pac12 to have no presence in Southern California, but with the growth of other teams and USC's recent issues, competitively the league would still be a top league. There's plenty of money outside USC so it's not like the Big12 without Texas. It would hurt for sure but the league would be ok. The Pac12 has enough depth that I don't think there are 2 teams that would bring it down.