College currently mostly exists as an early-life service, but alternative paths exist: in the US, people in the military can go to college later in life. In some countries, people can get college education at evening courses. We could envision that some people starting early in life in physically hard jobs may want/have to retire years earlier, and use that time to go through college our of personal interest.

This isn't really possible with an onerous college system mostly dedicated to social layering, but an university system with scholarships for everyone and flexibility in the time and way people enroll is not an impossible goal.

I for one would really like to return to university after I retire, for instance.