I am becoming a fan of John Calhoun, a 20th century scientist who dealt with the effects of population density. He performed some experiments on rats where he build rat cities where all of their needs, except infinite living space, were taken care of. These rat utopias all had the same end, population growth until a point when the behavior of rat society fell apart, followed by a complete and permanent collapse of the rat city.
His experiments became very famous, and were debated endlessly as to whether they applied to humans. Then he sort of fell out of fashion. But if he is correct, these Chinese cities, no matter how successful they are, or even because of their success, will be the cause of the collapse of China.
You’re right Beijing hasn’t though about all the social implications of urbanization. I met one official touting his urban plan but when I asked him how he would deal with the rise of street crime, he looked clueless. It seemed as if he had never pondered this dilemma before proposing China megacities as the wave of the future.