> reinvent better uses of the existing urban layouts as people are stuck with them.

They are most certainly not.

Many car-dependent cities, large and small, are depopulating, quite rapidly. (Some at over 10% population loss per year!) This depopulation doesn't come from a city's urban core(s), usually; but rather specifically from the areas of these cities worst affected by car dependence — the sparse fringes of suburbia, and the exurban developments. (The people living in these places have the most car-centric, non-urban-infrastructure-reliant lifestyles to begin with; so when they get a better job offer somewhere else, they are unfettered from simply packing their things in their car and moving. This makes these suburban fringes and exurbs much more vulnerable to depopulation during low-employment periods, housing-affordability crises, etc.)

For many cities, these depopulated fringes and exurbs have nobody left in them at this point to care what happens to the area; and so, in response, these cities have often been literally shrinking, de-incorporating these exurbs from themselves, in order to avoid paying infrastructure costs indefinitely for roads and pipes and wires that nobody is using.

And after 10-or-so years of this state of de-incorporation and abandonment, there is nothing of value left in these places to directly move into and reuse. A perhaps-surprisingly constant amount of maintenance is required, both of buildings and of infrastructure, to keep both from falling apart.

• Suburban SFH homes in North America — usually stick-built, and usually in boreal-forest conditions — that have gone un-lived-in for more than five years or so (and not left in the hands of any bank’s or property developer’s maintenance company), are almost always a total write-off, not worth attempting to repair: they're inevitably mostly rotted, the rain having gotten in at one point and made a home for humidity and mold/fungus, destroying the structural integrity of the framing. (You might be able to save homes that have sat in desert climates like Arizona, but these have their own problems related to fast oxidation of metals, incl. electrical and plumbing. Maybe concrete+plaster Mission-style architecture can be saved; but after 10 years of disuse, you'd still need to gut the building to get it livable again.)

• An exurban "low-CapEx high-OpEx" asphalt road grid, that hasn't been driven on in 10 years, is no longer drivable: asphalt does not survive 10 years without maintenance, even if nobody is driving on it. It's likely been undermined over time with huge numbers of small sinkholes — sinkholes that will become innumerable potholes when the first person brave enough to drive down the weathered road runs over them. The roads would need, at least, to be mulched up and spat back out by a road re-paving machine (with a refill and resurface of the undermined subbase + subgrade layers in between) to make them safe.

If you're going to have to do both of those things to make conditions livable again in that area — raze all the buildings, and recycle all the asphalt — then you may as well do all the razing and asphalt-mulching all at once, first — and so end up with a fresh and empty terrain and a pile of materials, ready to be re-laid out in whatever (hopefully more compact!) fashion you choose.