If we have the source and it's easy to test, validate, and deploy an update - AI should make those easier to update.

I am thinking of situations where one of those aren't true - where testing a proposed update is expensive or complicated, that are in systems that are hard to physically push updates to (think embedded systems) etc

Legacy code, not the running systems powered by legacy code

If you’re still an AI skeptic at this point, I don’t know what sort of advancement could convince you that this is happening.