> All the software engineers we need for the next 20-30 years are already in the current workforce.

There's no way of knowing what the industry will look like decades from now. Even assuming the prediction that seniors become 10x more productive, that would mean software becomes much cheaper to produce. Does that induce enough demand for additional software that keeps employment levels high? Could be, who knows.

Alternatively, maybe software hits a saturation point where there just isn't as much new ground to cover and employment levels crater. That could happen too.