First of all, I am not a huge bronco fan and lean toward making a change. However..
Bronco is a decent head coach (though he would be an excelent D coordinator at a big school). The reality is that the currrent slide of BYU football has very little to do with Bronco. The reality is that byu football was doomed the moment their rival was invited to the dance and it was left behind. The only thing that would offset this harsh reality would be if Utah ended up being a 2-3 win bottom feeder year in and year out. With this not happening, BYU has very little to hang its hat on and will struggle recruiting players in an already small pond.
With there being very little chance of BYU being made relevent in college football in the next 10 years, recruits will go away, ticket sales will go down and all this in an era of there being pressure to fork out more money to not only the coaching staff and facilities, but also players.
I would be shocked if byu football surives the next decade and is still around (in any relevency). BYU fans are pissed when they sense the writing is on the wall and lash out at the current coach and admin. The current reality is a very tough pill to swollow and bronco has the unfortunate timing of being the man at the helm during the inevitable collapse.