There was a point a few years ago when Nick Saban wanted Alabama Football to play only Power Five teams. Since no other college football coach agreed about Power Fives playing just Power Fives, the lofty goal was unachievable.
Such a change might happen in college football someday, but it would require a different bowl structure and also probably no more than a Power Three consolidation.
Thanks to the historical data provided by mcubed.net we know that among current Power Five teams, there are only 12 teams the Alabama Crimson Tide has never played.