From Take-Two's call today.
Source: http://ir.take2games.com/phoenix.zhtml?c=86428&p=irol-newsArticle&ID=2193198Take-Two said:Announced that Sid Meiers Civilization® VI, the next entry in the award-winning turn-based strategy franchise that has sold-in over 35 million units, is currently in development for PC at Firaxis Games and planned for launch on October 21, 2016.