Of course, since "Revenge of the Rust Belt" is in the NYT business section, it's really not seriously claiming that the Pittsburgh Steelers victory presages some reversal of the massive and (relatively) recent migration to the Sun Belt, represented for the purposes of this trope as the vanquished Arizona Cardinals.
In fact the author argues for continued migration based on a (interestingly visualized) correlation between average January temperatures and population growth for US cities (since the last census I take it). So the title's a little misleading (and a false promise of hope for this Chicagoan).
However (and interestingly for a liberalish paper based in a hyperconurbanized Northeastern city and opinion capital), it's only in the comments that limits to Sun Belt growth are correctly discussed (water availability in the Cadillac Desert mainly, but also steeper growth in energy prices that make the essential air conditioning and resulting auto-centric sprawl - let's just say not quite sustainable).
But there's balance in the comments too: one mentions the fact that heating a building from say 20F to 68F consumes more BTUs than cooling one from 98F to 72F (this was pointed out rather effectively by Wired magazine in 2006). Another commentor points out that established Pittsburgh is culturally less open to newcomers than new Phoenix (Dunno. Maybe. It's plausible I suppose).
And in the "what gives" department, another commentor claims that the Pittsburgh shrinkage figures only consider the city of Pittsburgh itself, not the metro area, and implies that this was not consistently applied. I would agree that comparing MSA growth may be more meaningful, especially when one of the types being compared is a newer sprawl which tends toward annexation models for growth.
Still the author gives a very nice industrial-geographic historical analysis of the rise and decline of the industrial Great Lakes and Ohio Valley cities that has a transportation cost basis. As a transportation and logistics geek, that stuff rings true and fine.