I just took a look at BYU's football schedules over the next few years and...WOW. Power schools don't schedule non-power schedules are regularly as BYU gets scheduled. Just saying, but they are a power quality school and should probably be considered as such.
Example: Idaho's independent schedule in 2013 - North Texas, Wyoming, Northern Illinois, Washington St, Temple, Fresno St, Arkansas St, Ole Miss, Texas St, Old Dominion, Florida St, New Mexico St
Example: New Mexico St's independent schedule in 2013 - Texas, Minnesota, UTEP, UCLA, San Diego St, New Mexico, Rice, Abilene Christian, Louisiana-Lafayette, Boston College, Florida Atlantic, Idaho
Comparing these two - NMSU definitely had a tougher road to hoe, but let's look at BYU's scheduled opponents between 2016-2020...
2016 - Arizona, Utah, UCLA, West Virginia, Toledo, Michigan St, Mississippi St, Boise St, Cincinnati, Southern Utah, Massachusetts, Utah St
2017 - LSU, Utah, Wisconsin, Utah St, Boise St, Mississippi St, East Carolina, San Jose St, Fresno St, UNLV, Massachusetts, Hawaii
2018 - Arizona, California, Wisconsin, Washington, Utah St, Boise St, Northern Illinois, Massachusetts, Hawaii, Utah (2 open dates)
2019 - Utah, Virginia, USC, Washington, Toledo, Utah St, Washington St, Boise St, Massachusetts (3 open dates)
2020 - Utah, Michigan St, Arizona St, Utah St, Boise St, Northern Illinois, Missouri, Stanford (4 open dates)
I'm not totally convinced they should even join a conference given their ability to schedule strong. Even their G5 scheduling is fairly difficult.