Maybe only in the "zones" (I doubt FFXV is completely open-world) and at the edge you would hit invisible walls ("There is a storm ahead!", "Noct, the clouds are too thick, better turn around!" or something like that). Of course it won't be easy to design the world so that you can't sequence break and also their streaming tech would have to be optimised for that from the ground up. Though, the summon sequence in Episode Duscae already shows dynamic LOD even from all the way above the actual location where the party is, so who knows, maybe they'll manage to have some sort of mini airship like the Niflheim army uses to fly a few feet above the area. I assume the reason why the summon sequence shows a close-up of the summon and Noctis first for a few seconds before moving completely out with the camera is to mask the asset load-in, so they probably will have to mask it somehow, too, when entering an eventual airship and also when descending.
Definitely not an easy task, that's why Tabata was so hesitant when talking about the possibility of having it in the final game.
lus.
