In this case, the problem will fix itself, because suburbs are the Cold War creation, they can be seen as a compulsory wartime measure. Provided that relationship with China will not reach Cold War standoff levels, they will cease to exist by themselves, because modern people really don't want to live in them.
It's to even really true in cities that people perceive to be growing and vital. New York City, for example, would be shrinking if it wasn't for the influx of foreign immigrants: https://zicklin.baruch.cuny.edu/wp-content/uploads/sites/10/....
> The City of New York grew by over 362,000 residents between 2010 and 2016, a growth rate of 4.4% (Table 1). City officials consider this to be among the strongest periods of growth in the last half century (NYC Planning, 2017a). The population grew by 402,000 people through natural increase, and net foreign migration added an additional 500,000 residents. Net domestic migration was -524,000, as more people moved out of the city than moved in.
At least in the US, I doubt this is true, by and large. Given the sheer number of people in them, it seems to strain credulity that most don't want to.