The biggest problem I have with believing a super-league is a viable enterprise is the situation details of a matchup for less than obsessive fans.
Take, for example, Ohio St and Oregon. They played an OOC game against each other in 2021, back before anyone could conceive that they would be in the same conference in a couple of years. Week 2 matchup, #3 Ohio St vs #12 Oregon, Primetime, ABC. It got pretty good rankings because it was an early season game against ranked teams that rarely play each other. There was novelty to it because these two don't play regularly and a lot of other top teams were tuning up against cupcakes.
Let's flash forward to 2029. Oregon has been in the B10 long enough for some of the novelty to have worn off. Week 8, #12 Oregon vs #3 Ohio St. Primetime game, ABC. Is this as attractive of a game to fans other than the two schools/B10? Probably not.
Edit: Wanted to add, a Super Conference probably tanks the value of the CFP. Rematches would be fairly common, and historically, the ratings suffer when that's the case. There wouldn't be nearly as much novelty to watching two teams that rarely play each other to draw in more casual fans. There would be comparatively little to distinguish the playoffs from the end of the regular season.