BYU's current situation has as much to do with the changing landscape of college football as it does Bronco.
While aspects of Bronco's approach -- both within the game and beyond -- drive me nuts sometime, I do believe he cares deeply about the players and winning, and has been very good overall for the program.
I don't feel replacing Bronco with any of the currently discussed 'alternatives' will produce a different result, unless the college football landscape shifts in BYU's favor, or until BYU begins to take a fundamentally different approach to the program (which is HIGHLY unlikely).