Atlanta is abandoning Turner Field and building a new baseball stadium elsewhere. Of course there’s plans for revitalizing the area, but I expect little. A square mile of unused asphalt will indeed blight the area.
I'm no fan of the Braves organization but they have been lied to by every ATL regime since the days of Fulton County Stadium. For decades city officials promised to develop and curb blight around Fulton County Stadium. Then Turner Field is built across the street in 1997 with the promise that the city will redevelop the area as part of the deal.
Fast forward a decade or so and the Braves ownership sees the area continuing to decline (from its already declined state...) and know they have to do something as fans will not venture into the city as potential targets, no matter how good the team is (well...in this case, was...). They had been studying and polling demographics of their attending fan base for a few years when they announced the move up I-75 to Cobb County, at a location just outside the I-285 perimeter, opening in 2017.
Oh, by the way, the city regime is now promising to redevelop the area for the next tenant. You just can't make this stuff up...