Well they can use real world locations for inspiration for the in game, so they have a lot to work with in terms of making it all look good, and adding in the fantasy elements.
They can bring back basically all the old school FF enemies, and it's still shown that even the same species come in different colors and sizes for variety, places to farm for crafting mats if there is even such a system.
Mini-games, fishing, chocobos, maybe platforming sections where Noctis can warp from point to point and get a high view, more stuff I probably can't think of.
Hidden Chests, Hidden Dungeons, Armiger weapons, Accessories, Regular weapons with their own abilities EX: Blood Sword with Drain Blade ability.
All in all the overall size of it will indeed simulate a real road trip with some buddies.
So I don't doubt this will be a good thing.