Different ages don't consider different teams bluebloods. Anyone that pays attention from 6th grade to age 60 knows NU/Bama/OU/USC/Texas/Michigan/OSU/PSU/ND/LSU are the bluebloods, with some debate about schools like FSU/Miami/Georgia, but that's about it.
Different people will have different opinions on who's elite based off of what year it is and recent success more than age. Michigan State was elite until they won like 2 games or whatever it was last season.
I strongly disagree. Your age should and does affect which teams you consider "elite" or "blue bloods" because both terms are subjectively defined and not static.
If you took a survey of 7 to 18 year olds in America on which teams are blue bloods I doubt Nebraska would Crack the top ten of that list.
I'm not so sure we can really say one way or the other. Alabama sucked when I was young in the 90s but I knew they were a blue blood program because of things I heard from family, friends, etc. And if you listen to broadcasts of our games every year, announcers still use language like "tradition," "powerhouse," and "blue blood."
Though, they're often used to describe our past.