In my experience working with large financial institutions and banks, there is plenty of running COBOL code that is around the average age of HN posters. Where as a lot of different languages code is replaced over time with something better/faster COBOL seems to have a staying power in financial that will ensure it's around a very very long time.

I wasn’t aware of this until that talk, but COBOL essentially being both the logic and the database together makes it very sticky.

What do you assume the average age of HN posters to be?