The 3DS was first shown at E3 2010 and launched in February 2011. Given that there is no advantage in having a 1.5 year long gap between reveal and launch, there's no good reason why Nintendo shouldn't change the timing this time around. The gap between reveal and launch certainly didn't help the Wii U because Sony and Microsoft had plenty of time to downplay everything. As for the games, the release schedule of the past and the upcoming months for both the Wii U and 3DS should serve as a good hint that at this point all Nintendo is doing is bridging the gap until their new hardware launches.

There are doubts about the exact meaning of Kimishima's recent statements because the translation was questionable. But more importantly, the available pieces of information point towards a 2016 launch:

1. NX will have a (for the most part) shared library and different form factors for the hardware.
2. The 3DS is already five years old and in need of a successor.
3. The Wii U is far from a healthy platform and should be replaced rather sooner than later.
4. The current release schedules for both systems are largely devoid of EAD games and those are the first teams that make software for new hardware.

If NX launches in 2017, then only because Nintendo couldn't get it ready as planned.

They probably could have shown the NX last year, but then what? Wii U sales are so shitty they would've cratered and 3DS handheld shipments are Nintendo's lowest in like 15+ years ... so they can't afford for those to go any lower either.

There was literally zero benefit for Nintendo showing the NX last year, the only thing it would have accoplished is hurting what's left of the Wii U/3DS' likely last full holiday season. 

Nintendo announced the N64 just two years into the SNES life cycle too ... lol ... things change, you can't keep operating the same way forever.

Your 1. is 90% assumption without any facts.

bdbdbd, the only information Iwata ever said about NX is that it's hardware.

So everybody just imagined in May 2014 when he said they plan on offering a unified architecture & operating system similar to iOS that will allow for easy porting to and from devices along with the possibilty of increasing the number of form factors and stating they will revolutionize gaming in about two years? Ya that must have been a dream.

Not quite, didn't Iwata use Ios and Android as an example of their approach on NX, just that instead of an operating system that would work on multiple hardware, Nintendo's plan is to have one hardware that just would have multiple form factors (because of games being programmed directly to hardware). Iwata also told us, that Nintendo need to unify the architecture because it can't support two different devices anymore without causing a games drought for the other. If Nintendo developed the same game for 3DS and Wii U, they'd need to make the same game twice.

You do know that NX isn't supposed to be "one hardware", but "Nintendo hardware from now to an end"? If the market determines Nintendo needs something else, then they'll make something else for the market.