That's a hell of an assumption. I know people who live in NYC, making very good money, and they're all crammed into tiny apartments with multiple roommates because the congestion and rent are so ridiculous. That's fine for people in their early 20s, but do you really think these same people are still going to live in NYC once they get married and have kids? A small percent will buy a place in NYC, and the rest will move out to the suburbs.
If anything, I'd predict that small and walkable urban areas, interspersed inside large suburbs, are more likely to be the future growth areas.