What happens to a software engineer when full feature completeness and bug-free-ness is achieved? What happens to a police employee when zero crime is achieved? What happens to a builder when all the buildings that ever need to be built are built?
Even if you get to the point where you can say "there are no problems at all!" (doubtful, except maybe in tiny startups or similar), adding "and there will never be any more and we never have to do anything ever again" is hopelessly naive.