No game is perfect. The GTA series is getting quite close, yes, but there are so many things it can improve upon. There's also so many scenarios out there they can do. In fact, I have an idea to mix two Rockstar-made games in GTA and <GAME>, but am debating whether to actually send them an e-mail because I feel they might just pass it on by. Do you think they'll actually take suggestions? (Reason I don't say is because I don't want anyone trying what I'm SERIOUSLY trying to do. So what if I'm paranoid?
Anyway, so many options are still open. Hell, they seem to have a fascination with aliens. Make a futuristic GTA flying cars would be awesome. GTA is far from over, let me tell you.