This basically is the one comment closest to what I think about the situation.

3DS sales are definitely declining, but the New 3DS definitely was used to try and remedy the situation since they are not likely to release a new handheld within the next year and need some more stable sales.  If the New 3DS does well enough, they could postpone the next handheld a little.  Even if it doesn't do well, I do not think they plan on releasing any earlier than 2016.  

Of course, Nintendo COULD go around and release in 2015 if they have some kind of new idea that revolutionizes the way we think about handhelds and console gaming that wouldn't totally hinder the progress made by releasing the New 3DS, but I think that's the least likely situation.

N3DS is coming in 2015 for west seems to go against announcing new handheld...2017 earliest

2017/2018

Nintendo announced the 3DS the same month they launched the DSi XL in North America, lol. 

The DS was first announced less than a year from the GBA SP launch too. 

These things mean nothing to Nintendo. They release either new handheld revision or a new handheld entirely on a yearly basis almost. 

N3DS is not a big product launch for Nintendo, it's just the typical "need to get one last revision in" thing for Nintendo. 

What does everybody think 3DS sales will look like in the next 2-3 years? I'm thinking

2014, 10-11 million

2015, 8-9 million

2016, 5-7 million (depending if successor releases)

That's probably spot on, and also why Nintendo simply cannot wait until 2017. They can't sustain themselves with 3DS sales that low, and no the next Nintendo fan who waltzes and says "don't worry, Wii U will carry Nintendo until 2017!" needs to stop drinking the kool-aid. 

Nintendo has never had handheld shipments lower than 10 million since the mid-1990s when the Game Boy brand was temporarily fizzling out (before Pokemon), which is why Yamauchi allowed the Virtual Boy experiment to go ahead because they needed something else to sell. 

Sub-10 million shipments of portables for Nintendo is a "danger zone". 

2016 will be last year with Nintendo support.

No one cares about the new 3ds.

Even if we look at the DS-3DS transition

Last 3DS revision (DSi XL) launch in Japan in November 2009. 3DS launched in Japan in Feburary 2011.

That's roughly a 14 month gap. 14 months from New 3DS to Fusion would be Feburary 2016. So a March-May 2016 launch in Japan would actually be a little longer of a gap.

Ditto for the US, DSi XL launched in March 2010, 3DS launched in April 2011 ... 13 month gap between the two.

GBA SP-DS was about a 1 1/2 year gap.

In fact I'd say the New 3DS' timing hints fairly strongly at a new handheld generation beginning in 2016.

Not only that but AMD reports that they huge "two major vendors" that are big contract wins for them regarding an ARM based AMD mobile part for 2016. 

That sounds an awful lot like Nintendo could be one of those contracts, especially when Iwata said he wanted future Nintendo platforms to "absorb" the Wii U architecture in some way (that probably means they have to use AMD). So that all lines up rather nicely. 

This argument wouldn't convince me because of the rise of the mobile market.  Since the mobile market seems to have shrunk the dedicated handheld market share, that 10 million shipment argument might not really hold up as well.