The concern on birth rate fall is based on habitual thinking. People are used to present economic model. We are at door of AI age. Millions, probably billions of production line workers, drivers, teachers, lawyers, doctors... will lose their jobs. Unemployment will be biggest social problem.
The world will need more creative people, less skilled people. For human resource, quality will be more important than quantity. Relatively low birth rate is necessary.
it is estimated that human life expectancy will reach to 100 years in the next 50 years.