The new ability to rebrand teams in Franchise was a big step in the right direction. If we could add to that the ability to change the number of teams and divisions and/or leagues (as exists in on-line custom leagues) that would make it even better, especially for those creating historical teams and leagues. I recognize it might be challenging generating schedules for leagues of differing numbers of teams, but that should be doable.
Perhaps this can be added to MLB 21 The Show.
I really hope this is the plan
And maybe you can also delete teams so people could do rosters from before the 1990s
Team expansion and contraction would definitely be a welcomed feature. Any players on teams removed from your league could be added to the free agent pool or hold a contraction draft.
This would be an amazing feature and would truly allow franchises to be played from an historical perspective. If High Heat baseball back in early 2000 could do this with a variable length schedule I can't see how a game couldn't almost 20 years later.
Would also love to see some sort of stadium creator as well, although I prefer to play in the old time stadiums, but may be the addition of more classic stadiums would suffice.