I think that New York is built a great deal on the nostalgia of the period that [one] just narrowly missed, and I think that's what attracts people to coming there—the mythic notion of what New York has been. I hesitate to say, "Oh, it used to be great, and now it's not good anymore," but I think that there's no question that it has become a city defined in part by how expensive it is, and expensive cities become less diverse and less interesting, because the interesting stuff tends to be the stuff around the margins.
Writer Susan Orlean makes the cliché migration from too expensive NYC to the greater creative spaces of LA. However, her restraint from shoveling dirt on the more legendary destination is well met. Her New York may be dead. But your New York, young writer, is busy being born right now. But you aren't moving there for what will be. You are moving there for yesterday, like Woody Allen's paean to the golden eras of Paris.
In this sense, migration is a lagging indicator. You go where you know. You go where the buzz is (was). The social human is risk averse. No one rolls the dice on a place that might, or might not, become.
For Rust Belt cities, this disposition is a burden. Yesterday's Pittsburgh lacks appeal. Furthermore, social media celebrates a Census release like a harbinger of things yet to be, but sure to happen. Yesterday's numbers portend tomorrow's boom town.
"[T]he interesting stuff tends to be the stuff around the margins." - Susan Orlean
Orlean's assertion is as true for geographers as it is for writers. Buried beneath the headlines of booms and busts, at the edges of the data dump, lurks hidden trends yet to entice the young and geographically fickle. The Rust Belt is dead. Long live Pittsburgh.