Nintendo NX, the next console from Nintendo, is expected to release in March of 2017.
The release date of the platform was revealed in the financial result documents of the company that were published earlier this week. In the documents Nintendo claims that the console will be "a brand-new concept" though no further details were given.
The name Nintendo NX is most likely not the real name of the console. Nintendo often uses codenames to reference upcoming products. For example, the Wii was codenamed "Revolution" and the Gamecube was codenamed "Dolphin".