Rockstar revealed new details on GTA 5's online modes, dubbed Grand Theft Auto Online, this morning. According to comments made by Rockstar North president Leslie Benzies in the latest issue of Game Informer, the game's much-anticipated online mode is set to expand greatly into the future, and those expansions may include an entirely "new" city in the form of Liberty City. 

The goal, Benzies said, is "to create an entire Grand Theft Auto world that consists of everything we've done or are going to do then let the player freely move between them."

This comment - specifically, "everything we've done" - suggests that cities that have appeared in past GTA titles may very well be fair game for GTA Online. Since players can supposedly travel between these worlds at will, it stands to reason that each will be totally distinct from one another and will be quite large in their own right.

While worlds that may appear have not yet been confirmed, it stands to reason that GTA IV's Liberty City would be the first to appear in the game's online suite. Worlds from GTA: Chinatown Wars and other past titles shouldn't be ruled out, either - at this point, just about anything is possible.