New York's problem (or more broadly, the problem of medium density)

After reading yet another blog post talking about how New York is losing migrants to other cities, I had an extremely insightful date.  My date was with a woman who lived in Flatbush, at the outer, more car-oriented edge of Brooklyn.  She drives everywhere.  When I told her about my youth in Atlanta, she seemed downright envious: where I saw slavery to cars, she saw "quality of life" (English translation: cheap land). 

And I can see why.  If you are going to drive to work, there's no profit to living in New York: you get all the hassles of the city (high rent, heavy traffic) without the benefits of a pedestrian-oriented lifestyle- and that applies not just in suburbia, but even in urban areas with Walkscores in the seventies.  Just the fact that you can walk to the grocery store does not compensate for the high rent.

So it would seem to me that migration from the outer boroughs is more common than Manhattan- and in fact that is the case.  Out-migration statistics show that Manhattan gets as many domestic newcomers as it loses to the rest of the state, while Brooklyn and Queens (as well as the majority of suburban counties) have lost migrants and gain population only due to birth and international immigration.

This explains why so many New York suburbanites have moved to the South and West: once you cross the line from subways to driving, a little additional driving is outweighed by cheap real estate.  So it doesn't make sense for New York or any other city to keep replicating suburbs and imitation suburbs.  To compete for people, New York either needs more Manhattans or lower rents.

Now of course, there are some medium-density neighborhoods in New York that are very attractive places to live.  But it seems to me that to compete with the Sun Belt, they have to be a lot more attractive than they would be in a lower-priced market.