It will be tough to get ahead of NYC2 and Orlando. Also, I think San Antonio would be in front of them as well. So after those teams, maybe if Atlanta is drawing enough fans to its games regularly they'd get a look from the league.
I don't disagree with that at all. However, if both Orlando and NY2 are up for consideration, I feel like MLS would want to be a 24 team league. Something about 22 teams seems odd.
So you have:
Orlando
NY2
San Antonio
then whatever is up for grabs possibly St. Louis, Atlanta, San Diego, Detroit (that Silverdome project), Minnesota