Odds of Hanging On
If you do your job well, show up on time, and get along with everyone else, you'll continue to have a job. A roadie finds work through word of mouth. If the word in the biz is positive about you, you'll be in demand for as long as you want to do it.
Then again, you may not want to be spending every day on a tour bus or tossing guitar picks into an audience when you're fifty years old, so it's up to you to decide if and when you want to settle down.