They stated once that the appearance of elements from other series isn't because the worlds ade connected, but for the nostalgia. They explicitely said FF XIV is it's own universe

Quote Originally Posted by ObsidianFire View Post
It's just a reference. The Crystal Noctis has a connection to in XV is very, very, very different then the (Mother)Crystal we have a connection too. And by all accounts, we've got a much better deal going then Noctis does...
You sure about that? With all the hinting, Shadowbringers, the idea that light is not good and we have yet to learn the truth about Hydaelyn, I guess we could've picked a short straw as well...