All I have heard/read, is that they are stopping (for now) at expanding to 16 teams (USC and UCLA joining in 2024). I don't think they have made a final decision on how the conference will actually look in 2024. Whether it will be one big division, still East and West or potentially 4 "pods". Personally, I like the 4 pods, kind of like the NFL. I saw this structure being thrown around:
Pod A: Indiana, Maryland, Purdue, Rutgers
Pod B: Michigan, Michigan State, Ohio State, Penn State
Pod C: Illinois, Iowa, Northwestern, Wisconsin
Pod D: Minnesota, Nebraska, UCLA, USC
This could expand the Big10 Championship to 3 games. With the top team from each Pod getting in. More money for the Big10.
One thing that seems common, rivalry games will be maintained. So Michigan and OSU would always play, Badgers-Gophers, etc.