Digitimes: Nintendo NX will be released in 2016.

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Soundwave said:

20 million shipment target for the 1st year is massive, that heavily suggest a portable hybrid or multi-form factor line of hardware.

Unless Nintendo has some new magical sex toy controller there's no way they're hitting 20 million with just a vanilla console + controller gimmick, their brand is far too weak in the console arena for that. 

Also XBox 360 (unveiled May 2005), PS4 (unveiled March 2013), XBox One (unveiled May 2013), Nintendo DS (revealed May 2004), and Nintendo 3DS were all released several months after their unveilings. 

So really it was just Nintendo's consoles that weren't following the industry standard. No one wants to see something exciting and then be told they can't buy it for 18 months. 

Estimates are in line. I believe 1 year statement means the first full year (12 months). Put 14-15M on the handheld part and 5-6M for the homeconsole. Nothing impossible.