The resume of a New York City local actor suggests that Rockstar Games has already started work on the next installment of Grand Theft Auto.
The link to the resume of the actor is here :
http://resumes.breakdownexpress.com/751904-3340379
The resume (and the motion capture) means that Grad Theft Auto has already been in development for quite some years, and the final touches are being given, before the code is written and work actually begins on incorporating the videos and stuff in the game. This can mean that GTA 6 can be a reality by 2019, or 2020!