A conference isn't a conference when you do not play each other ... we are already there ... getting to 16, 18, 20 or 24 is just another level.
I do not understand how you can grow larger and NOT have divisions. There is no way IMO to (a) have equitable scheduling - and (b) accurately determine a conference champion when you do not play each other.
I would suspect if you get to 18, 20 or 24 you then have to have separate divisions with the champion emerging from the winners of each division. If you want to have two 10 team divisions with 9 divisional games plus maybe one cross over. Or if you want to have 4 five team pods with 4 pod games and then a matchup with another pod for 9 total games then OK.
One of the unresolved issues with conference realignment is scheduling ... how is that going to be solved?