This is not hard to figure out if there are only 16 teams.
No divisions needed
3 fixed rivals you play every year
12 teams you play 50% of the time, play 6 out of the 12 each year.
9 conference games total.
Now if they end up with 18 teams, then you would have only 1 fixed rival and 16 teams you play 50% of the time.
If they go with 20 teams, you could have 2 fixed rivals, 8 teams you play 50% of the time, and 9 teams you play 33% of the time.