In a long interview on Game Trailers Kojima has cleared up some confusion around the latest Metal Gear Solid game.
He says that Ground Zeroes and The Phantom Pain will be released separately. "We can't comment just yet on how these things will be distributed and sold," he said. Ground Zeroes, the prologue, will come first, Kojima said, and will introduce players to the gameplay "on a smaller scale."
He also confirmed that David Hayter was not asked to reprise his role as Snake / Big Boss due to the desire to set this game apart from the others.