Junichi Masuda has finally announced next Pokemon game titled as Pokemon Black 2 and Pokemon White 2. It will be very first time Pokemon game franchise that a numerical sequel of game will launch. Previously there has being a different color in Pokemon game.
Junichi Masuda also confirmed that the game will launch in Japan this June for DS (it will be compatible with 3DS). The official website of Pokemon game also confirmed Pokemon Black 2 and Pokemon White 2 for US.
No details has been revealed apart from this. You can check out teaser site for Pokemon Black 2 and Pokemon White 2.