No. Data centers are divided between Physical Data Centers (JPN, NA, EU, OCE etc) that contain 1 or more Logical Data Centers (Aether, Primal, Crystal, Elemental etc). Cross Data Center play is only for logical data centers that are in the same physical data center and therefore the same physical location. OCE is a physical data center that only contains one logical data center, Materia. So for players on OCE nothing is changing. They have stated that they would like travel between physical data centers eventually, but that is not happening at this time.