There is a way to make the existing economic system more sustainable. Any nation could adopt it — with a single legislative Act.

Currently, there is a political imperative in every nation to maximize total output in order to maximize employment, total income, and the collection of taxes. With this change total output would be governed, passively but effectively, by demographics. There would be no unemployment or poverty at any level of total output. There are built-in protections against inflation.

A brief overview is in "Permanent 'Quantitative Easing'" (here in Medium, but not behind the paywall). Personally, I am convinced that "To Preserve What We Have, What We Have Must Be Enough" (also in Medium but not behind the paywall).