Level 91-99 Content (OUTSIDE ABYSSEA).

[Masekase]

I think SE has already hinted about this actually. If you pay attention to your cutscenes from Abyssea quests, it will become somewhat clear.

The new end-game area will be:

Moon.

Think about it. We have sky, and sea. Watch and see if i'm right.

Moon has always been around its behind moon gate.