Automation is the answer. Food, housing, medical care are the main things for the aged out for the society to take are about. Automation will solve food. Less people less housing needed. And the medical care productivity will be significantly improved by the automation.
Currently growing population seems to still be an economically net-positive thing as we still need people in order to do new and bigger things. I think though that soon it will become net-negative as average person's total lifetime productivity will be losing to automation and you don't need 20+ years to start the robot up and 20+ years to take care about that robot once it got worn out. In that situation we'd better have less people yet more educated, trained etc. in order to be productive beyond what is replaceable by more and more automation.
Currently growing population seems to still be an economically net-positive thing as we still need people in order to do new and bigger things. I think though that soon it will become net-negative as average person's total lifetime productivity will be losing to automation and you don't need 20+ years to start the robot up and 20+ years to take care about that robot once it got worn out. In that situation we'd better have less people yet more educated, trained etc. in order to be productive beyond what is replaceable by more and more automation.