I don't know what part of the State you live in....with the younger kids(teen-ages in particular) where I live BYU is NOT dominant anymore. Way more University of Utah fans....because they know they can actually go to school there and there is a recent(last 10 years) history of athletic success that BYU hasn't had. Getting into a BCS bowl would have helped BYU in more ways than just finances.
I think the kind of people who spend time on Cougarboard are very unlikely to switch sides, but for the less blue-bleeding audience it's more about what have you done recently and who won the last game than 20+ years of loyalty. Losing to Utah over and over has definitely not helped....even when they didn't make it to a bowl game they still beat us.