2 more years. Both WiiU and 3DS will have successors in the same year.

I'd say that Nintendo knows that WiiU has been a failure but that they also know that rushing their next console could prove a terrible mistake if they don't do it right.

With that said, I'd like to think that Nintendo will still support the WiiU for another 2 or 3 years and then launch a well thought, named and marketed console by Xmas 2016 or 2017.

3 more years, 5 years in total

6 years and one month.

Lolll I didnt notice :/

Nintendo sunk the money into this thing, ending early would be silly. They're going to try to maximize software sales on WiiU before transitioning.

I'll say 2 more years at least.

I think Ninty's goal is to make a Wii U that is mobile (aka Fusion) but will be rebranded and hh/console sold separately (possible combo deal). For next gen Nintendo has to make the hardware compelling, and that is the lesson Ninty must take from this current gen, its not ALL about great games (which Wii U has in abundance).

The WiiU will have a minimum 5 years cycle. I think new console will not be late 2018.

2012-2013 -Launch (New Super Mario Bros U, Nintendo Land, Pikmin 3, Wind waker HD)
2013-2014 - Super Mario 3d World, Donkey Kong Country: Tropical Freeze, Mario Kart 8, Bayonetta 2
2014-2015 - Super Smash Bros Wii U, CAptain Toad, Splatoon, Mario Maker, Yoshi Wooly world
2015-2016 - Zelda Wii U, Xenoblade Chronicles X, Star Fox, Retro Studios TBA game
2016-2017 - Mario Galaxy 3? - Animal Crossing?

2015 Peak Year.
I want 30m+ sold LT.
I [currently] expect 25m.
I want it to last until 2020
I expect it to last until 2019 - where at end of Year new home console releases.
(2018 for 3DS successor. And Vita, if there will be one.)