The question has been raised previously. You could be forgiven, though, as it's no doubt fallen off the front page of this section of the forums... As noted above by Enkidoh, all allusions to other FF titles are just that: Allusions. Homages. References. A wink and a nod. Can we make predictions based on what has come before in previous FF games in connections to the materials that have been appropriated by the devs for use in FFXIV? Oh hell yes. But as for Hydaelyn actually being Ivalice, Terra, Nova Crystalia, The World of Balance, etc, so on, and so forth. No. Hydaelyn is Hydaelyn. This did not stop the devs from wanting to create a very faithful adaption of FFIII's Crystal Tower in 3D using modern graphical technology. But this does not mean we are in that world, it just means that the devs really liked the Crystal Tower and thought that we'd appreciate a faithful reproduction being a part of Hydaelyn.