My first thought at the mention of Ayatlan was that we may see it in the expansion. Given how much the development team have been dropping hints about airships and flight it's safe to say we'll be visiting some sort of equivalent to FFXI's Sky and Ayatlan would fit the bill nicely. We know SE like to lead us into new content with story rather than just suddenly unveiling it.

I've been entertaining the idea that Ayatlan could be more than just the Ixali homeland though. The moogles also claim to have descended from their home in the 'heavens' where the Twelve dwell. It would not surprise me in the slightest if we later come to discover that both their mythologies share the same origin.