I don't think it'll be in Columbus again. The last year it was there (2008), it was during Origins so of course you had to pay $60/person just to get into the convention center and the hotels were booked. Another thing I heard that there was supposed to be a cap on number of players and that Origins messed that up by giving Masters some of the Junior's passes, etc...
St. Louis they moved because there was little food within walking distance and also the fire marshal had to come in because there was a fire hazard with too many people.
Then we get Indy which has food, big enough space, and a lot of hotels downtown. I don't see why they'd change it if it's working out fine. (Although I wouldn't mind them changing it because the same place for 3 years gets a little boring after you do things so many times.)