If a business needs to run a piece of code, to me this also implies actively maintaining it. TonyM subscribes to the write and forget view which may also be the view of many others, including corporates, but I think that dev paradigm is very risky and short sighted.
Important code, whether it is mission critical or not, should always be in active maintenance. Code which is no longer needed, can be junked, but if any code is still used, even if just once per year, it should be in the active maintenance pool and assigned to one or more coders to keep up to date.
I have my own projects and I actively maintain everything which my business depends on. I also engage in code reviews every 3 months and refactor code if needed.
I do not subscribe to the “if it ain’t broke, don’t fix it” paradigm. I believe that all code is inherently broken (has bugs) and constant code reviews, refactors, rewrites, are there to eradicate bugs and improve my code.
If the language changes, code must also change. That is the only dev paradigm that makes sense, because progress is a good thing and we should not hinder it.