Look, there's no proof that it won't be on the NX.
Let's all take a quick history lesson, remember Zelda U being shown at E3 2014, but it was missing during E3 2015?
That's because it's being released on both the Wii U and the NX, but they haven't actually revealed that yet because the NX hasn't been officially showed off yet (coming at this years E3)
This is also why they didn't show off any gameplay, the game will most likely be a cross platform game on both the 3DS -AND- the NX or even Wii U
You're free to disagree, but don't spread misinformation that it's exclusively for 3ds