The "Braves left Atlanta" argument is so based in fantasy. The stadium is just, and I mean just, outside I-285, which everyone touts as the border of Atlanta. My parents live 10 minutes from the stadium, in Cobb County, and have an Atlanta address. The new stadium is about as far north of downtown as the old stadium was south, it just isn't technically in the city of Atlanta. never mind that the Atlanta Metropolitan Area is universally considered to be made up of Fulton, Dekalb, Clayton, Cobb, Gwinnett, and Forsyth. The argument of the Cobb Braves is a dumb rallying cry from those of my fellow southsiders that are too stubborn to admit that most of the wealth and disposable income exists in the northern half of the city.
The arena and location of arena will never be a hurdle to the NHL returning here. The far greater issue is the optics of two teams having come and gone. I would anticipate decades before another chance may come. It will take a team in need of relocation in conjunction with one rich owner a-la Arthur Blank that is committed to having a team in Atlanta and making it work, regardless of the cost.