Theoretically, there could be a championship matchup of Syracuse vs. Pittsburgh. If the game was in Charlotte, it would be a miracle if the stadium was even one-third full.
The SEC has a few advantages when it comes to its Championship game that other conferences don't have. For starters, Atlanta is a fairly central location. It's a reasonable drive from South Carolina, northern Florida, as well as most of Alabama, Tennessee and Kentucky. So plenty of fans can still make last minute travel plans if the championship game matchup is not determined until the week before the game. There's also no shortage of flights to Atlanta. Weather is unlikely to be an issue... the game is indoors, and most of the SEC states will not have problems with winter weather in early December that would impact travel to the game. The championship game matchup is almost always a good one, and fans will gladly travel to see the game.
Starting this year, the Big Ten Championship game will probably do better. There will probably be a lot more OSU vs. Michigan championship game matchups in the years ahead. Indianapolis is a short drive from southern Michigan and most of Ohio, so fans from both schools can get to the game easily so long as the weather is decent. Also, an OSU vs. Michigan game is far more likely to get people who aren't fans of either team (including Indianapolis-area residents) to come see the game in person, as opposed to a matchup like Wisconsin vs. Nebraska.
ACC just doesn't have the same dynamics. The schools in the conference are spread so far apart geographically, and a last moment trip to somewhere like Charlotte or Jacksonville just isn't feasible for many fans. And of course, football fans at ACC schools just don't have the same enthusiasm for football as fans at SEC or Big Ten schools. Miami has enough trouble getting their fans to come to their home games, let alone trying to get them to go to Charlotte.