It's about 10 or 12 who dominate the college football space.
ND doesn't care a lick about Utah. They don't compete in the same hemisphere when it comes to brand and draw. Same can be said with USC vs BYU or Auburn vs the Univerity of Washington. ND, USC, Auburn are on different planets when compared to the vast, vast majority of college football and the reach, influence and money their teams demand.
It never gets to 100 because there will always be incentives for the top echelon of teams to take their ball and go home.
If anything, the top 12 to 16 teams will make their own national conference and you can bet that any team from Utah won't be on anyone's shortlist.