I believe the company I work for is writing just under 500K lines of COBOL code per year... now... how much of that is "new" vs extending vs maintaining is a good question. It is very difficult to measure those things in our environment. If you were to ask the 60 - 75 mainframe programmers we employ, I'm sure they would answer that COBOL is very much alive, and no matter how hard you try to kill it, 40 years of system code is just not going away any time soon (depending on your definition of "dead"). Especially as we hire a good amount of "new to us" people to maintain the system.

I think individual companies should define a language as "dead" based on the number of new people needed to maintain the systems. As the number approaches less than 5%(?) of your replacement hires, have you effectively "killed" the language? At the very least it is on life support, and a decision needs to be made about its future. (A grim analogy, I know).

Well, are we talking dead or just obsolete? It can't be dead if it's actively being developed with significant amounts of money and tooling improvements (eg MicroFocus). It can be obsolete, though, if it's taking up a tiny percentage of new code or hires as you said that keeps going down.

I agree one should try to phase out something on life support. Gradually at the least.

5 million lines really isn't that much in the grand scheme of things.

It's not a lot. Yet, it's extra code extending critical apps with billions of lines of code and running more transactions than Google does searches. That's a large impact in the grand scheme of things.

Also, how much C was being written in UNIX 1.0 days outside of ports of same, exact software? :P