Thinking more on it, I think a team is a blue blood if it's been an elite level type program as long as most viewers (primarily focused on older viewers) remember. It's not something you can get to or fall out of in a decade, but as more and more college fans view a team as being a good before they were born, the more they will think of a team as a blue blood. On the flip side, if too much of your success starts falling outside of living memory, you start to lose that status. Instead it is thought of more as a history fact that a team was once a power more than anything special with the program.

Unlike other things in the sport though, the perception of teams being blue blood type of programs is generated more from older fans than younger ones. I think if your 40-60 year olds view a program that way, it tends to be viewed like that. Gradually those fans get older and the perception will die out if success is not maintained at an acceptable level.