Developers redoing "the entire world" seems to be understood differently by each person mentioning it. As someone said above they won't scrap the whole world and make something instantly better, animated and memorable. It's going to be patch up work. If their engine allowed them to manage world objects' animations easily and they were capable of utilizing such feature efficiently, the current world wouldn't be as static to start with.
You also ought to realize that asking them to put a lot of dynamic world objects in the game is already asking something the current generation of mmorpgs hasn't really accomplished effectively. Then again, i feel the world of FFXI was already more dynamic and much more memorable than FFXIV's, starting with the way you board a ship...