So, my dream scenario...
4 super conferences, with 3 or 4 tiers in each conference.
Elite Tier of each conference is 9 teams, plays every team every year.
Then another tier of probably 9 teams, plays every team every year.
Then 1 or 2 lower tiers.
So, effectively ... Big Ten as the ELITE level (well, the top 9 teams), and then the bottom dwellers of BigTen and top of MAC are the mid tier... and then whatever is left in the bottom tier.
SEC ... top 9 teams as ELITE, and then some of Conference USA and finally Sunbelt (SEC will have Elite, Mid, and TWO lower tiers)
ACC ... top 9 teams as ELITE, then BigXII /AAC as mid (and lower tier)
PAC ... top 9 teams as ELITE, then BigXII /MWC as Mid (and lower tier)
THEN each SUPER conference has some kind of promotion/relegation program to move teams from Elite to Mid to Low and visa versa.
SEC = 9 elite + 9 mid + 14 to 18 lower (because there are ALOT of teams in the south)
ACC = 9 elite + 9 mid + 8 or 9 lower
BigTen = 9 Elite + 9 mid + 14 to 18 lower (because a lot of schools in the northeast)
PAC = 9 Elite + 9 mid + 8 or 9 lower
Something between 116 and 120 teams total