Medieval cities are perfectly scaled for their inhabitants: people. Even a 10-year old feels comfortable and confident walking their streets. Cities of the industrial age are perfectly scaled for their inhabitants: automobiles. But these are monstrosities that will not outlast the end of the this era. It can be no other way. Except for the last 200 years, most people always traveled on foot. Their cities reflected that. Lasting cities of the future will reflect that as well.
Questions to ponder: will we simply leave the industrial cities, and let time and nature reduce them? Or will we stay, and instead carve them up into human-sized communities that will resemble cities created 1000 years ago?