For iterative upgrades to Nintendo hardware they tend to announce very close to the release date. However, the NX or whatever it tends up being called is rumored to be a reboot for Nintendo. So far all we know is that they have r freed to it as a brand new way to interact with games, and that it is coming out in March 2017. When asked at shareholder meetings Nintendo president Kimishima has said they can't release details yet because they are afraid that the competition will copy them.
To me this means that Nintendo is doing something very different from the gaming boxes from Microsoft and Sony. Something they think their competitors can mimic in short order, as was done in the past with Kinect and PlayStation move. But all signs point to the NX being a portable system. In a world where Sony and Microsoft seem perfectly happy to concede that market to Nintendo, can anyone see a scenario where S and M chase Nintendo down the road they have dominated for years only to be threatened by Apple and Samsung?
Whatever Nintendo is doing, the speculation is getting out of control, with fake leaks popping up non-stop. I'm almost getting fooled by the fakes, just because I want to hear something from the Big N so bad. They are going to have to speak about this soon. Many say that they are going to do so at this conference, or that conference but I think its going to be a Nintendo Direct again. They can carefully craft thier message, make sure there are no hiccups, and then to get it in the hands of players, they will probably partner with Best Buy or Gamestop, (insert your countries game shop of choice here).
The one thing that we know about the NX is that its coming in March, so Nintendo needs to start talking soon, we just can't wait any more!