Atlanta has two major league baseball stadiums in the works for their area:
Check out some sports market analysis on this wikipedia article:
U.S. cities with teams from four major league sports
.........a snippet of it.
States with all four leagues represented, but not in one metro areaAmong those states that have no metropolitan areas with all four sports, only Ohio has teams in all four major sports: the NFL's Cincinnati Bengals and Cleveland Browns; MLB's Cincinnati Reds and Cleveland Indians; the NBA's Cleveland Cavaliers; and the NHL's Columbus Blue Jackets, the only one located outside Cleveland and Cincinnati.
See more expansion and relocation talk for football, baseball, basketball, hockey and soccer on my blog (starting in Feb 2014, see table of contents/archive): Major League/Pro Expansion <CLICK> http://prosportsexpansion.blogspot.com/
And please feel free to contribute your two cents with mine.