Not a fact, it has already been in america, now it was in france, i suggest somewhere in eutope, like sweden.
It is the place of birth of minecraft and most swedish speak perfect english.
Holland could be an option too. Everybody speaks english, its central in europe, it has good flightconnections and enough room to house peopel (although that wouldnt be a problem anywhere).
That'S exactly my mind!
Minecon should be in Sweden or Germany!