This is actually a brilliant idea for a classic theme of FF to be instilled on XIV. The 'overworld' idea wouldn't be hard to do, even with inaccessible current zones (the clouded idea actually nods back to FFMQ anyways when you haven't unlocked that bit yet.) Landing could just be zoning you right where you would zone in with return or teleport so the same code from then on could be used, with the added bit of your airship phased in, hovering over the aetheryte of that zone.

Unfortuntely, since this is:

A) Fun
B) Actually uses basic FF story progression ideals
C) Requires more work than copy/paste/re-color

It won't get considered... Seriously though this would've been a cool addition, also with the bit of it being alternative to instanced housing.