8.0 speculation

[Cleretic]

Other than small context clues from flavor text painting it as vaguely pre-colonial America, the Tural (f.k.a. New World) we know - with it's diverse geography and myriad cultures - did not exist until it was determined to be the setting of Dawntrail and developed to fill that role. The same goes for any and all areas of the game developed, which is to say Ilsabard exists but is just ill-defined until when (or rather if) it's slated to be the site of our latest adventure. It's not a blank void waiting to have chunks of reflections slotted into it.

Also as far as other locations we haven't been to, Ilsabard is fairly defined, debatably more than Tural was pre-Dawntrail. We've got Landis, Corvos, Dalmasca, not to mention places that are on the Ilsabardian continent that we already have been to like Werlyt and Bozja. They mostly haven't been pinpointed on the actual map, but they're all THERE.

It's the least blank of the voids that we haven't conclusively mapped!

[Cilia]

Also as far as other locations we haven't been to, Ilsabard is fairly defined, debatably more than Tural was pre-Dawntrail. We've got Landis, Corvos, Dalmasca, not to mention places that are on the Ilsabardian continent that we already have been to like Werlyt and Bozja. They mostly haven't been pinpointed on the actual map, but they're all THERE.

It's the least blank of the voids that we haven't conclusively mapped!

The fact most of those are Ivalice derivative, and the ones that aren't (Werlyt and Corvos) have been minimally explored, suggests to me that if they're saving the rest of Ilsabard for anything in particular it's so Yasumi Matsuno can use it as his personal sandbox when or if they're able to get ahold of him.