Odds of Hanging On
For the most part, once an astronaut always an astronaut, provided your physical and mental health hold up. But that's not a guarantee.
If and when you choose to leave the job, there's still a bright future ahead. Where do astronauts go when the active missions end? Right back to what they were doing before they donned the space suit.
The military astronauts return to fighter jets and defense contracting, while the civilian crew can go back to engineering or physics or wherever else they came from. Astronauts might choose to hang around Mission Control doing experiments or giving talks about NASA and the space program.
Or you could run for office. If you can survive the never-ending void of space, you might be able to survive politics.