I can understand the concerns of being delayed beyond 2016, but no fear, It will come next year for the 30th anniversary celebration, like Skyward Sword for the 25th. They are not going to skip the opportunity to use the game to generate more sales for the Zelda console editions that they must be planning at this point.
The most probable answer: the game doesn't has a release date for the NX version, and both will be announced at the same time.
Our real concern is if Nintendo will be lazy to only release a big Zelda adventure game every 5 years...
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Prediction: No Zelda HD for Wii U, quietly moved to the succesor
Predictions for Nintendo NX and Mobile