Then there's this. Gassee is quoting from a May 2007 USA Today story ...
“Fatality rates for drivers begin to climb after age 65, according to a recent study by Carnegie Mellon University in Pittsburgh and the AAA Foundation for Traffic Safety, based on data from 1999-2004. From ages 75 to 84, the rate of about three deaths per 100 million miles driven is equal to the death rate of teenage drivers. For drivers 85 and older, the fatality rate skyrockets to nearly four times higher than that for teens.”Driving a car is cognitively demanding. Performance drops off for most people at age 65 -- traditional retirement age.
We're not going to be able to extend the knowledge worker's employment life until we can slow the decline of the human brain.
Of course this is before we factor in the effects of epidemic Diabetes.