GTA 6 (Grand Theft Auto VI) is Rockstar Games’ rumored sequel to GTA 5 (Grand Theft Auto V). GTA 6 will likely be released for Xbox One, PlayStation 4, and (If like Grand Theft Auto V) PC at a later date.
While GTA Online was Rockstar Games’ immediate focus following the release of Grand Theft Auto V, the studio is already considering possibilities for GTA 6. “We’ve got about 45 years worth of ideas we want to do,” according to Rockstar president Leslie Benzies, “We don’t know what GTA 6 will be, but we’ve got some ideas.”  A leak to Tech Radar indicated that development has begun on GTA 6 .
Rockstar has confirmed development on GTA 6, and they have stated that they would like to create one Grand Theft Auto game with all previous cities from the series. In an interview with Digital Trends, Rockstar North head Leslie Benzies said he envisions players being able to travel back and forth to revisit places they explored in past games. 
“Of course at some point we would like to have one big world containing all our cities and let the player fly between them and revisit their favorite areas,” Benzies said. “In that context re-imagining Vice City would be very interesting.”
As of March 29, 2016, Rockstar hadn’t settled on a location. They had previously scouted Tokyo, but this is not a confirmed location for GTA 6 .
Carcer CITY (and possibly chicago and toronto)
Dave from GTA 6 fan site GTAist provided the following video looking at the latest concept map of the midwestern United States in which we look at not just the possiblity of Carcer City, but two new cities based on Chicago and Toronto.
Some fans speculate on the belief that Rockstar could return to San Fierro and Las Venturas (one or both) to complete the remaining territories not found in Grand Theft Auto V. Due to console limitations and resource devotion, only Los Santos and Blaine have been covered, but fans have shown an interest in other San Andreas cities, as depicted by GTA 6 fan website GTAist.com.