I think USC will fire their coach this year. The biggest problem they have is recruiting. In 2019, 3 out of the top 25 California recruits chose USC. In 2018, 9 out of the top 25 California recruits chose USC. The 2019 recruiting class ranked 20th which is the highest ranking they have ever had in the 247 database. For 2020, they are currently ranked 43rd with 2 4*s and 10 3*s. In 2018, they had one 3* recruit.
USC is one of the best jobs in the country and you can win a national championship there. Any football coach would love the opportunity to coach at USC if offered. My guess is USC will go after Meyer as he seems a good fit. If Meyer turns them down, I think they look for the best current college head coach available and I would think Babers would be on the list of candidates.
UCLA is another matter. That is a tougher job with less institutional support and Kelly's contract would be tough to swallow. My guess is that he gets at least another year to try to right the ship.