Imagine a futuristic world with only a few hundred million people worldwide and a stable and eugenic birthrate around replacement level.
Ban single-use plastics outright and incentivize metal/wood/glass/porcelain etc for other applications. Biodegradable, chemically inert and much more aesthetically pleasing.
Much more localized energy production, even as local as household to household using solar panels, geothermal heating etc.
Most families living on a homestead with a garden and some basic animals the wife can take care of inbetween cooking and knitting. Most people living in or near villages under 1k pop. The majority of freight moving on rails, most people getting around on bicycles, small dogsleds, horses, buses, maybe some electric vehicles. It would mean a slower and more natural way of life, we could make our finite resources last a hundred times longer with minimal pollution. Mental health issues and obesity would evaporate. Our nuked endocrine systems would recover, etc.

I realize the incentives or political will for anything like this doesn't exist because the oligarchs demand a large population of consumers to milk and bilk. It's partly why the third world is pouring into the west right now. More warm bodies means more people buying toilet paper. If they're on a living wage or taking welfare is irrelevant.