SPOILERS After playing the 3.56 patch, it looks like Shinryu is also in game, and I'm starting to think that FFXIV has showed us the true origin of these two beasts, since maybe these are the real versions who have appeared in FF5, FF7, FF13-2 before they're banished to the Rift... So, the FATEs idea for the new area can take place after their banish.
Also, Here is my design for the White Raven mount idea.