In reality, how many older programmers do you know who are
   still coding professionally?

Strange thing - at my current company there are eight developers and all except me have been with the same team (although in a few companies on paper) for towards ten years each. One of them has been a programmer for almost thirty years. It's not mainframe maintenance or something else that would easily explain it - we use modern languages and frameworks. And our whole business is integration work between different nasty protocols - notoriously messy work. I can't exactly say why it works, but the leadership have the special sauce. I joined in February as a developer although have migrated into support roles following an interesting project.

The recent pg article about artists needing to be able to ship was interesting. We have testing but also get a lot of flexibility in what we can roll out and it's solution oriented rather than perfect-code oriented.