Six years past end of vendor support. Still running. One question.

The system runs. It does what it's always done. Nobody wants to touch it.

That's fine, actually.

But here's the question worth asking:

Who in your organisation actually knows how it works?

Not 'has used it.' Not 'could probably figure it out.' Actually knows.

The business logic. The edge cases. The reason that field is the way it is.

In most organisations, the answer is one person. Maybe two.

That's fine - until it isn't.