> People ... couldn’t imagine returning to the city which continued to decline.
I begin to wonder whether the demise of the city was really caused by the government subsidies of the suburban lifestyle. It's not that Levittown isn't sustainable anymore, it's that it never was, not on a long term scale. Low density living should be expensive because it is expensive. The government chose to invest in suburbs instead of the city. The city rotted without investment, exacerbating the problem.
It's only the last couple decades as governments tightened their coffers that the suburbs have had to carry their own load- and they can't.