But the real situation is even stronger to my point, because most software in use today won't be in 30 years. So the real graph for established products is that you continue to get new users for five or ten years as young people learn and old people die, but never enough to even hit the halfway mark. Then your company folds or gets out-competed by something else, your user base falls off a cliff and the software becomes irrelevant.

The point at which "new users" are the majority of the user base never even happens.