DHH's "As I Remember London" (paulbjensen.co.uk)

If you want the stonks to go up you need economonic output to go up. Hence societies have really two choices. 1. Import poor(er) people who are willing to work and make babies. Hopefully with enough integration the social fabric will not get destroyed, and economy can grow stronger. 2. Close the borders and slowly disappear from earth (both economically and physically). This can only be avoided if robots indeed materialize and can defend and carry the babies of the declining societies.