With the free agency debates going, how long a career can one expect from a player has come up. Lets dig into the history.
Some basic figures to start using data from the Lahman Database (available for free in MS Access format, SQL, and others - updated through the 2019 season, since it is a labor of love he updates when he gets a chance so I expect 2020 to be added at some point in the next few months).
By decade born, ignoring the 80's and beyond as many are still active. Last player born in the 70's who was active was Ichiro who retired in 2019 after playing 2 games.