Not sure if Kentucky has to push anyone out...
Oscar, Reeves, Toppin, Fredrick, and Wheeler are all seniors that transferred to Kentucky. They all could return with the covid year but I don't think Cal would want any of them outside Oscar to do that.
As for possible transfers I think Daimion Collins might look elsewhere, he's a 2nd year top 15 player and hasn't gotten more than 8 minutes a game so far despite playing in 51 games. Could also see Ugonna Onyenso transfer out, just a freshmen but Cal chose to burn his RS by having him play in 16 games this season top 40 kid when he came out too. With Toppin and Oscar potentially leaving he could see more minutes, but Bradshaw is a top 5 national ranked 7' that's incoming and you'll also have Ware and Collins back as well (if he doesn't transfer out).
Adou Thiero was a 3 star top 200 CG in last year's class, he might be someone that leaves seeing that the incoming class has 4 wing players all top 50 national players in it and his chance to play behind them as well as Wallace & Livingston could be limited.