You all do realize that suburbs existed before the invention of the car right? American infrastructure is bad but it’s not irredeemable, the assumption that we can’t provide public transportation to these places because of a lack of resources is malthusian. And sure some places like the American Southwest and Florida are legitimately over human population carrying capacity due to climate change but in general the earth as a whole isn’t, and cities like Amsterdam are just as unsustainable as Miami since even though has one of those le epic reddit notjustbikes cityskylines approved infrastructure, both are below the sea level.
I think in general our message should be abolish the need to own the automobile, any measures meant to limit car use should target the rich before the poor. And that trains are good, and that a high speed train across the United States would be a rather popular project in the eyes of even the chuds. And by god stop calling for the suburbs to be razed, stop trying to be zoomer Robert Moses.
Low rise options like cluster flats are generally what I'd consider medium family count housing options, certainly smaller than high-rises.
Other options like row houses or townhomes are a good low family count housing option as well. I don't think most people need individual houses, and lots of the older Streetcar Suburbs and similar in the US and here in Canada are generally based around small apartment buildings and rowhouses.
I used to live in Toronto, which definitely has heat island problems. Crappy in summer and not as helpful in winter as one might hope. But it's even more of a concern in the US, where things are getting really hot as well.
Cluster flats are also more pro-social. I've always been much happier sharing a kitchen with my neighbors because it usually turns into shared meals and a lot of community in a way you don't get in apartments.