IMO, BYU is the hardest job in the nation to be successful at and you nailed all of the reasons. I think Bronco really did show us the ceiling and he saw the writing on the wall when he couldn’t push that ceiling any higher.
If I was an up and coming LDS coach, I wouldn’t touch BYU with a 10-foot pole. You might catch lightening in a bottle one year and hit 10 wins but there are too many obstacles in the way to succeed consistently. Flame away and call me a dooms day poster but I think BYU is in a crisis in this day and age of CFB and teetering on the edge of further long-term mediocrity.