Odds of Hanging On
The NFL's oldest cheerleader, Laura Vikmanis, turned forty-six in 2015, and it's so unusual for cheerleaders to be that old that they decided to make a movie about her (source). For the most part though, this is a young woman's game. The minute you can't kick yourself into a full split, you're out.
If you do want to come back to the limelight after a grueling season, there's no job security or points for seniority—you'll have to re-audition every year along with the rest of the squad.