According to the placeholder by Tesco, the next Call of Duty will be called Call of Duty: Ghosts. The listing has the game releasing in December, but most Call of Duty games are released in November. The box art was also leaked as part of the placeholder which can be found above.
It will still be set in the Modern Warfare series, but the game is set in the future. The game is listed for both current and next gen systems.