I read somewhere that R* numbers the games that they feel will stand out in the series.
GTA: Released in 1997: You play a criminal in a free roam world. Undergo missions or do whatever else you want, rob banks, steal cars...
GTA: 2 - The sequel to the 1977 hit. Much improved over their first venture into what was to be one of the most successfull video game series' of all time.
GTA: III - Introduced 3rd person view, a much greater interface and HUD, and many more features.
GTA: Vice City - Introduced helicopters and aircraft, Home ownership, Increased the number of vehicles and weapons, not a huge improvement.
GTA: San Andreas - A vast map, high level of customization, storyline and minigames significantly improved, reworked camera system, improved money system, ability to swim, removal of loading screens when in transit, hundreds more features I don't have time to write about. Mabye R* underestimated San Andreas?
GTA: IV - More realistic, not just in terms of graphics, but in terms of design, much more in-depth storyline, Multiplayer is introduced, successful DLC released, once again... too many to list. Apart from it cost close to $100m to develop.
GTA V - Could this be the perfect combination between San Andreas and IV?, a mixture of a large and realistic map, upgraded RAGE engine providing even better graphics, even more customization than seen in San Andreas, use of MotionScan?, so much to speculate, and so long to wait
We will just have to wait and see what the next trailer brings us
Let's take a different tack on this. The version of L.A. featured in GTA:SA was massively, massively condensed. They really had to hack L.A. to pieces in order to come up with something that would fit into one corner of the playing area. Even though I don't live in L.A. (hell, not even in the U.S.) and don't know L.A. half as well some people here, I know that there are a quite a few significant landmarks (Farmer's Market, La Brea Tar Pits, Disneyland, Universal Studios, Hollywood Bowl and many, many others) that didn't make it into the final cut of Los Santos in GTA:SA. And stuff that did make it in was cut down, compressed, rearranged and massively compromised in order to make it work. True, L.S. was never intended to represent L.A. street for street, it only had to have the right feel. And that was enough for the story that was to be told with it. But it doesn't change the fact that it was completely and brutally butchered to put it into GTA:SA. (Not that SA wasn't a bad game or that LS was a bad city. I like GTA:SA.)
In GTA:V, Los Santos now gets a whole game to itself. It too will not be a street by street representation of the real life city. But nor is it going to be a rehash of GTA:SA's version of L.S. But it is going to take centre stage. L.A. will still be massively condensed, but now they have much more area to play with, so it won't be compressed quite as much. They are going to be able to get a hell of a lot more of L.A. into the new L.S. This rendition of Los Santos is going to be an entirely new city. It will be as different from GTA:SA as GTA:IV's Liberty City was different to GTA:III (albeit that in GTA:III LC wasn't intended to be a direct representation of NYC, but I digress).
Furthermore, I think it unlikely that GTA:V will be focusing on L.A.'s street gang culture. In GTA:SA, it was central to the plot and the lead characters. GTA:V may possibly have some street gang elements in it, but they are more likely to take a back seat to what ever the central plot is likely to be.
Overall, GTA:V is not going to be GTA:SA mk2. It's going to be it's own game with it's own identity. It may not be what everyone wants. But Rockstar do prefer to let their creativity do their talking. They will give us a game that breaks new ground and is able to stand in it's own right.
GTA:V is going to be different in so many ways to GTA:SA. Deal with it.