I think he's talking more about urban renewal than new urbanism. After all, it's not very conservative to hollow out the city then move on to somewhere else.
This is the market (people) making personal choices to exercise their freedom of association. Cities would not be hollowed out if the proper incentives are in place to attract that market segment that likes cities.
Broadly, the fix for crumbling cities is competitive bidding, cut the red tape, protect property rights, relax historic preservation laws and cut marginal tax rates.
With a maze of zoning laws, licenses, regulations, a difficult labor climate and an overall tax burden that is still too high, cities are their own worst enemy when it comes to fostering entrepreneurship and attracting the talented and creative, says the Mackinac Center for Public Policy.
With the right package of incentives, cities can flourish. Stealing private property under the socialist anti-sprawl scams is theft.