I just feel, and obviously, this only my opinion -- the days of elite OOC matchups are numbered because of the sheer number of elite matchup these teams will face in conference play (especially in the SEC, with the addition of not one, but two teams who could be top 10 type teams). I understand what you are saying regarding fans loving to watch those games, but the teams definitely don't enjoy playing them.
Those elite matchups are usually hard hitting matchups, there is no resting starters, the risk of injuy is higher and teams already struggle with depth because of the portal and all the transfers, as it is.
That is just my thought pattern and also why I think ND will have no choice but to join a conference, because the type of games they'd need to keep their SOS up won't be readily available. I'm a UM fan -- if UM is facing OSU, PSU, MSU and then USC, to go along with whoever else they face in the B1G, Wisconsin, Iowa, etc. -- I can't see anyway possible they'd want to schedule ND too in the future? I'd think they would like to use the OOC to get the team in some type of rhythm in the 1st 3 games.
I could be way off base and schools continue to schedule those type of games. Hell -- maybe it is in the agreement with the TV contracts they sign? Who knows? Seemed like it'd be an interesting topic to talk about.