Keep in mind America was bulldozed for the car - there is precedent for large areas being massively transformed, and suburbs can absolutely be redesigned to be more walkable. A big issue with most suburbs is zoning that prohibits anything but single family residences. That means corner stores are literally illegal to build, alongside mixed use buildings, and other things that enable communities to be nicer to exist in, more friendly, and more convenient.
In addition to zoning laws, roads can be redesigned to be safer and more friendly to other modes of transit - and roads already need to be replaced every couple of decades, so theoretically within that time span every road could be improved in this way. More lanes have never reduced traffic in the long-term, but building infrastructure for denser modes of transit like busses or bikes or pedestrians does.
Older rural areas are actually typically much more walkable than American cities. Keep in mind, rural towns were very common before cars existed. They’re typically structured to have a small center, sometimes basically just a “main street”, with all the places you need to regularly visit, and houses surrounding them, and the farmland surrounding that. This way the people are all relatively close, and the farmland is not between you and others. These towns are all about self sufficiency within the community, but ofc if you keep a car for when you need to travel somewhere else that’s fine, and no one is begrudging you for using gas powered farm equipment on your farm. The main point is you don’t have a daily commute that requires a car, because it’s either your farm or one of the lose shops that are close to everyone.
And for what it’s worth, a lot of train networks used to go to these rural towns as well, and it’d be awesome to see those return for Intercity travel.