I do think this probably mildly underestimates BYU impact. So bump BYU up and say the three biggest losses will be Oklahoma St, Utah, and BYU (in some order). That's still a loss they can live with.
And if you argue that there's really only 20 teams that really make a difference in viewership and the rest is just difference in TV times and channels? Them those last factors are things controlled by the networks. So why include more teams to split the pie, when the reality is that the networks are providing the most valuable part - the exposure/availability