If I recall correctly, they did say GTA V will be bigger than SA, RDR, and IV combined, but they took into account not just straight square footage, but also enterable buildings and whatnot. I'm curious as to how many places will be open for folks to walk in and interact with. For instance, if we can walk into a hotel, will it just be nice interior graphics, or will we be able to walk to room, ring the bell at the counter, press the elevator button, knock magazines off the table, etc.
After watching the trailers and reading all of the articles, this has potential to be the greatest game ever created. The size of the game, along everything you can just seems unreal. It looks like the Xbox version will have to be multiple discs.