There has been a trend of fans leaving early or not showing up at all because of the boring home schedule. This requires Alabama to bring more interesting teams to Tuscaloosa. This is the main reason they have moved in that direction. There still isn't one single year where Alabama plays 2 P5s in their future nonconference schedules.
Alabama doesn't want to schedule like USC. USC doesn't even want to schedule like USC any more. Access for nonP5s to play P5s won't be dramatically different for the foreseeable future.