According to Loose Talk in the latest Game Informer, RockStar North is already working on the next instalment in the Grand Theft Auto franchise, which should be ready for release this holiday season.
"We're not talking about new DLC or a collection of previously available DLC, we're talking about a full retail game. We expect this title to follow the suit of previous GTAs and use a subtitle such as GTA: San Andreas, etc. Tokyo might be a possible setting for the game, but details are non-existent at this time." - Game Informer Issue 190
Vamos: que no es una expansión, sino el posible GTAV (O más formalmente, GTA (inserte ciudad aquí) para seguir la saga ViceCity, San Andreas, etc...) y que (a lo mejor) esta ambientado en Tokyo.