We currently have a global economic model that relies on population growth to help sustain and support GDP expansion. There is no country on the planet that has exemplified how to have a growing economy and a shrinking population at the same time.
We have a temporary problem as the final areas of the world undergo the Demographic Transiotion. In the time it will take them to complete the process, our global population will peak at 9 billion. But after that, predicted for 2100, our numbers begin an intractable decline. There are no new immigrant populations with high birtherightes that can be brough in to counterbalance the below-replacement fertiitkliy rates of native populations: EVERYWHNERE HASD UNDERGONE THE TRANSTIOIN. WE ALL HAVE BELOW REPLACEMENT FERTIOLITUY.
We might see this looming, catastropphic prblme of overpopulation; but for our children, their children, and most future generaitons (unless we innoivate/change our economic reliance on growing consumer popuilations) will worry about underpopulaiton. They will marvel at the time when the concern amongst us all was the unsustainabiltiy of a growing human poilation. Because they will liekly have underatken massive economic reforms in order to wrench the dependency of propsperity from the clutches of total number of consumers.