First, 1.0 had some loading screen between areas like Shroud and Mor Dhona. Second, 1.0 had big areas but they were also empty, full of copy/past assets and very laggy.
The actual game code is way too messy to allow big open areas to become a reality again (Kholusia is already out of memory, reason why the dwarf tribe is in Lakeland).
So if I would love to have a full open area (I hate loading screen) this is definitely not happening in this current game.

Nevertheless, I could see this happening for the original city states (and the return of the aquarium of the Hyaline in Limsa Lominsa?) and I hoped for it when they announced the revamp on some 2.0 maps to allow fly but that didn't happened. As we can see the full rendered Lower Secks from the Upper Seck in Limsa and vice versa, and considering the most recents cities are composed of one area, that seems possible to me.

That being said, that would leave Ishgard on the side as this city was created from scratch and not recovered from 1.0 like the others and I don't see how this city could be remodeled into one, the two parts being totally independent (looking from the heights of the Pillars, we do not see anything resembling Foundation, same from below).

I support the idea, but I think they have more pressing issues for the moment.