[twelvechairs]

Your link skirts the issue somewhat (though so does the OP).

The real change that has taken place in cities has not been 'more people in the [designated 100 years ago] city area'. It would be pretty much impossible for most of New York city's 'growth' to happen in the city area (at least, without removing planning regulations entirely). Demand is going up massively though. The inner-city 'slums' of the 20thC are very definitely not coming back and have been replaced by areas of affluence, which are pretty unaffordable to live in for most of the population.

The suburbs are changing too. People are using 'local centres' more, and paying more to be close to a nice one. So even the suburbs are less 'suburban' than they used to be.