The Pokémon Company International posted a press release today announcing the new game
Pokémon Super Mystery Dungeon (ポケモン超不思議のダンジョン) which will be released in Japan in the Autumn of 2015, North America in the Winter of 2015 and in Europe in early 2016.
Pokémon Super Mystery Dungeon - North American Announcement
Look forward to the launch of Pokémon Super Mystery Dungeon in winter 2015, continuing in the legacy of the exciting Pokémon Mystery Dungeon video games! With dungeon layouts that change every time you enter them, the fun never ends! Battle alongside Legendary and Mythical Pokémon to save the world from a crisis in a tale of unprecedented scale.
Europe Press Release - Latest Chapter in the Pokémon Mystery Dungeon Series Coming to the Nintendo 3DS
The Pokémon Company International and Nintendo announced today the upcoming release of Pokémon Super Mystery Dungeon for the Nintendo 3DS family of systems, the latest installment of the Pokémon Mystery Dungeon series that has sold more than 13 million copies worldwide. Pokémon Super Mystery Dungeon will be available in Europe in early 2016.
Players can look forward to even greater, randomly created dungeons that change each time they enter. In Pokémon Super Mystery Dungeon, players will battle alongside Legendary and Mythical Pokémon to save the world in a sweeping tale of adventure and mystery.
Sources:
http://www.pokemon.co.jp/ex/cho_dungeon/ and
http://www.pokemon.com/us/pokemon-video-games/pokemon-super-mystery-dungeon/