Straight from the horse's mouth in the Nintendo investor meeting, Mr. Iwata stated that they will need about two years to come up with a platform that will change the game business (at least for them). Based on his previous comments of wanting a iPhone-iPad like service based structure that decentralizes seperate platforms, this is almost assuredly the beginning of a Fusion-style Nintendo gaming future. 

It also means game development would probably have to start (well) right about now. It takes about 18-24 months to make a game and probably a tad longer for launch titles. I think it's a very strong possibility that the next EAD Tokyo 3D Mario is in development for this platform already. 

If the handheld variant launches around March-May 2016, then EAD Tokyo should be able to deliver a new 3D Mario for the launch with even a couple of extra months to stretch their legs a bit and not have to rush the game. I think that would be a terrific launch title, as Nintendo really cannot afford to f*ck this next launch up at all (absolutely 0 margin for error now). 

Tw years might be when they announce it, but releasing it that early would be a terrible idea. 2017 should be the earliest unless they want to be rolled over by Sony and Microsoft again when the PS5/XTwo come out.

3DS is not going to make it that long, 2016 is where it will have its fifth anniversary and will need to be replaced at this rate (it's no DS, by a long shot). Wii U is kinda irrelevant to Nintendo in a business sense I think, they are just content to ride that out and make sure it gets enough of its core IP, but it doesn't impact their overall business, a system that only sells 15-20 million units isn't good enough. Besides even by late 2015, Nintendo will have already released most if not all of their major IP on the Wii U already (after this year, really only Zelda and Metroid are left). 

FY2017 is where Iwata has said they want to start returning to big profits, that almost assuredly means new hardware has to be launched in advance of that. QoL is probably spring 2015, new handheld that signals the beginning of the Fusion era two years from now (spring 2016) sounds dead on. 

That will give them enough time to get both product lines out of their launch windows and begin to profit, assuming the public likes what Nintendo is offering. 

Wait, are we talking about a Wii U or 3DS successor? If it's 3DS I don't mind the 2016 release date, but I thought we were talking about the Wii U :P

It's both. From Iwata's comments there won't be a seperate console/handheld difference any more, there will just be hardware variants that all play the same games, like how iPhone and iPad share the same apps/iOS store. Though I could see the handheld variant launching in spring 2016, and then a home mini-conosle/hub variant using the same/similar chipset launching in fall 2016. 

I dont get it.

Calm down. Nintendo will wait for releasing anything new as long as they can. And there is good reason for that: technology advances in a pace never seen before.

Also don't forget that the Wii U has still a long live in it. They haven't even scratched the surface of whats possible with the GamePad. That why Iawata is saying that one title can change it all...

2017 at the earlyest.

In two years I can be dead. Come on Mr. Iwata and just bring it already.

I think the next Animal Crossing will be in the same boat. It will be a launch title for this future platform.

Nintendo has to get this right, it's probably most important launch in their company history, if they screw this up and have 3 bad launches in a row, it likely is curtains for them as a hardware manufacturer in the gaming business period.

It's just too many blows right to the face, a boxer is going to fall down sooner or later.

They have to get this next launch right and that means starting to plan for it now. A successful launch in this business really is made years before the system ever launches, the decisions have to be sharp and on point years prior to launch.