Too many things point to Ishgard being the theme of 3.0. Reasoning:

1) We have known for some time that Ishgard is destined to be Eorzea's 4th grand Company. naturally the implementation of a new GC would require surrounding zones. Perfect for an expansion.

2) Choco raising is a precursor to choco breeding which we were told isn't far away. Ishgard is the home of choco breeding.

3) In a Q&A video, Yoshi-P was asked about wyvern mounts for DRGs. He said they were coming and upcoming turns in the story would make it make sense.

4) Any reference of sky is likely reference to Ishgard's motto; "Of the sky. From the sky. For the sky."

5) The teaser at the end of 2.3.

I would be highly surprised if it wasn't Ishgard.