I see what you're getting at, but if it's not about age, why use an age related analogy? I probably should have amended my first statement in this thread is that it sounds ageist, if even implying that the people who will refuse to adapt will be older. This day is already here, people are already adapting to this. He seemed to frame it as the current young 20's career people will have this limited timeframe of productivity.
Age analogy is fine because unlike few who are deep into technology and latest changes in the field (which btw are over represented on this site) for most IT developers age => experience without actually improving skills.
As I interview lot of people for typical Enterprise IT jobs even at 20 years of experience they do seem to not know much beyond what they learned in first few years.