Something that would be cool to see is the creation of larger areas and somewhat merging of existing areas and their own instanced cities. I understand that doing this would create more strain and set higher requirements for both the server and client side. I personally think that it would make the game environment feel more alive and connected to their surrounding areas. An example could be Thanalan and connecting the surrounding area with Ul'dah so that there would be no loading between zones creating a more unified map.