[mhays]

These factors aren't about everyone suddenly deciding to leave. They're about influences.

In commercial real estate, the term "headwind" is common. A few degrees of added heat in Phoenix would be a strong headwind. The need to put your house on stilts in Miami would be a headwind, as would the taxes to raise streets a few feet. Or the seawalls around other coastal cities.

Over time, headwinds can act with geologic purpose on the rise and fall of cities, as they always have.