You're assuming that any productivity gains made by switching to git (or something else modern) would be overshadowed by the time and effort it'd take to migrate. I don't have any evidence either way, and I bet you don't either.
(Most) people don't use git (or hg, or whatever) because it's shiny and new, but because it gives them a better workflow and higher productivity.
As I said, I'm not assuming anything, and don't know either way. I suspect you don't either, so it's silly to reject the idea of migrating out of hand.
Why do you suspect that? I was an openbsd developer. I am quite familiar with their workflow, and cvs suits it perfectly well. There is virtually no gain for them to move to git, and a ton of pain.
(Most) people don't use git (or hg, or whatever) because it's shiny and new, but because it gives them a better workflow and higher productivity.