I think Nov 2016 honestly

Fusion is the successor to both the 3DS and Wii U ... there won't be a "traditional" Wii U successor.

So whenever Fusion launches is when the next Nintendo generation begins and Iwata basically has already said that will be in 2016.

"[T]he idea I mentioned about redefining the definition of video game platforms will also require approximately two years," Iwata said (May 2014).

I think Nintendo desperately wants to hurry up and kick off their unisoftware system, I just don't know how much N3DS (success or lacktherof) will influence the next gen release dates. Spring and holiday '16, for HH & home console seems like what most are predicting.  

Stop with these threads, 2017 is impossible, all you have to do is look at Nintendos track record releasing consoles, N64 was delayed, GC hardware was ready in 2000, but the software wasn't, Wii doesn't count it's an overclocked Gamecube and Wii U had it's fair share of pre-launch problems as well. Hell, I'm only new here, but I'd bet someone you won't be seeing a new home console from Nintendo in 2017, even 2018 might not be possible (though it is still likely, it depends on what route Nintendo go for). I could see Microsoft launching a new console in 2017, but that's only because they have the resources to do so.

2017.

2018, alongside the 3DS successor, in a Fusion format.

Why do you guys keep thinking there is a separate platform here coming? Fusion is the successor to both the 3DS and Wii U.

I don't really understand why it's that hard to understand. Iwata has basically spelt it out in his investor meeting comments.

- They will make a devices that's akin to Apple's product line ... meaning several hardware variants that use one software ecosystem like iPad, iPhone, iPod Touch all have the same apps and even a similar chipset.

- Nintendo has even collapsed their handheld and console teams now into one singular entity, there is no longer any seperation, this should be a pretty strong tip-off of what's coming. 

- This will launch approximately two years from May 2014 (so May 2016-ish).

That's straight from Iwata. The age of completely distinct handhelds and consoles with different software libraries from Nintendo is over. A "new definition" is coming in 2016 ... and that's direct from Mr. Iwata speaking to his shareholders. You guys are still thinking in the old, traditional paradigm, but Nintendo is going in a different direction. 

2017 is a safe bet; however, I would prefer a 2018 release date so that they can build a stronger launch line up than what they had for the Wii U.

Same.

Yep, this is what I see

Jan/Feb 2016-Nintendo Direct announcing both Fusion platforms with launch windows of mid-2016 for handheld variant and holiday 2016 for console version. Probably have 1-2 trailers for games slated for launch.

June 2016-at E3 they will give final details such as price/release date/launch lineup for the handheld variant. I'm thinking maybe June for Japan and August for America/Europe. Expect lots of demos/trailers for games releasing thru spring of 2017.

Sept 2016-Nintendo Direct showing going into more detail of games releasing during the holidays and into spring. Release date/price finalized for console version, which is Nov for America/Europe and Dec for Japan.