as something to shoot for. He's never stated it as a goal for any particular season, and has in fact stated multiple times that it would take back-to-back undefeated seasons to win a NC. He even repeated the back-to-back undefeated stuff after the installation of the playoff system, thinking that it might well take back-to-back undefeated seasons to reach the top 4 in rankings.
BYU has actually won a national championship before in the modern era. There is no reason why BYU, as a program, should not be striving for another championship as a long-term goal. Any self-respecting program in the country ought to have the same goal.
I realize your post didn't mention national championship, and neither did the OP. However, your invocation of the final four and Bronco setting too high expectations led me to believe that you are referencing Bronco's goal of winning a national championship. If I've made an incorrect assumption, ignore the above.