According to trusted Pac-12 Insider Jon Wilner, both the USC Trojans and the UCLA Bruins are "planning to leave for the Big Ten as early as 2024." He added that "the move has not been finalized at the highest levels of power."
Whether one likes this move or not, it was going to happen eventually. Either this, or something similar.
With Oklahoma and Texas heading to the SEC, the other strong conference needed to add a brand and blueblood like SC to create that 'superconference' so that they could make sure they could compete on a financial level. USC being in the Big Ten will also help the conference contend on the field as well.
USC football can still have much success in the Big Ten, while UCLA will continue to be a laughingstock.
When USC football has an elite coach, they dominate the Big Ten. The last time they had one (Pete Carroll), they played in five NY6 Bowl Games against Big Ten teams (one was for the National Championship). They won every single one of them, and the least amount of points they won by was 14.
They even beat Penn State in the Rose Bowl with the disappointing Clay Helton as the coach. It's a conference USC can win in. UCLA, on the other hand, can't win in any conference. The last time they even played in a New Year's Six Bowl game was before I was born, and sure enough, they lost to a Big Ten team (Wisconsin) in the Rose Bowl.
Now that the Trojans have a top five coach in the nation in Lincoln Riley, and one better than all coaches in the Big Ten but likely Ryan Day (and even some would say that's debatable); they can at least compete in the Big Ten by the time they get there (again, 2024 at the earliest).