First, thanks for a truly powerful essay.

As it happens, I do have a proposal to offer. It would make the existing economy (any nation's existing economy) more sustainable by having demographics govern (passively but effectively) total output. It would also accomplish more good things for the members of society. At bottom, the most important thing it does is to make the economy as a process more just. It can be implemented in any nation with a single legislative Act, so it could literally be accomplished (eventually) overnight. This idea needs advocates.

if curious: "Same Economy, Way Better Outcomes for Society" (here in Medium, but not behind the paywall)