Why 3DS CONSIDERABLY ?
Maybe will be down, but at least not by much because the new version.
I believe it will be down considerably despite the N3DS, not down just a little because of it.
Dedicated handhelds are quite simply going completely out of fashion, the 3DS has had two major revisions and some truly massive, system-selling software release and was down yoy in 2014, comparing the first six weeks of the year (including half a week from the end of December in both cases), the 3DS is up about 200k due to the launch of the N3DS in the west, with a 430k-ish increase due to these extra sales (likely more since the overall weekly sales were a lot weaker in the weeks before, it could be down was much as 250-300k or so yoy already). Before the launch of the N3DS; the 3DS was behind yoy globally by a fair bit and down 5-8% in Japan, the most important territory for handhelds, and after the N3DS launch.
The N3DS coming to Japan did not stop the decline and it will only get worse, launching in the west will not stop a decline either and will likely slow it down even less than in Japan. There isn't really any software on the horizon that is bigger than some of the mammoth hits already released on the platform either, it is perfectly reasonable at this point to expect a considerable drop in the 3DS' sales yoy. Once the launch effect of the N3DS settles, we'll see where the baseline settles; I'm thinking it will be below 2014's numbers and that this difference will increase as the year goes, eventually leading to a 15% drop or more in totals.
End of 2016 hardware sales:
Wii U: 15 million. PS4: 54 million. One: 30 million. 3DS: 64.8 million. PSVita: 15.2 million.