4. Economy
According to Dan Houser in Game Informer's magazine, he states that there will be a "vibrant and fun" economy. Property can't be purchased this time around, but Houser did state there will be other stuff to spend your money on. Alright, now I'm going to speculate (I can't resist). If GTA V is going to have a more detailed economy, does this mean we can finally trade stocks? One of the biggest problems with GTA IV was that there wasn't much to do after you finished the game - this was mostly because there wasn't anything to spend your money on. With the addition of stock markets, poker and customizable vehicles in GTA V, this problem should be alleviated a little.