From what I understand about how the OCA is planting missions in the metropolitan areas of Texas, it's not likely that one would just be planted in south Dallas out of the blue. Typically, what happens is that as more people begin attending services that are commuting in from another area, they'll form the nucleus of a new mission in their area. Then, as those missions grow and begin attracting more people from further away, they'll spin off new missions in those areas, with new churches basically spreading outwards from the established ones. If none are being established in south Dallas, it's probably because there aren't enough people from that area to form a new mission. I can't really speak to how the Greeks or Antiochians choose where to plant missions, but I would not be surprised if it's along similar lines.