[bombcar]

Single-family homes can get surprisingly dense, depending on how you move the numbers and sizes around.

But more importantly, all towns and most cities were at "suburban" densities years ago (check the "old towns" of most towns, etc) - the key was "travel to services" was limited by walking or sometimes subways, etc.

If instead of one Walmart every 30 miles you have smaller stores every 2-5 miles, suddenly density isn't as mandatory for livable cities.

Mixed usage and transit backbones are the key - you could design "pods" that are about two miles in diameter centered on train stations that would be entirely walkable/bikable - then you can even have the massive city centers.

People having cars isn't a problem if they don't use them for commuting, and some small changes in city design can lead to that.