It would depend a lot, I suppose, on whether the Wii U gets a well supported final year, or whether, like the Gamecube and Wii, it's left to rot for its last 12 months before replacement. I could see Wii U owners being fairly satisfied with a November 2016 replacement if 2016 has as many key Wii U releases as 2013 or 2014.

And I know the Saturn alone didn't kill Sega, and that Nintendo isn't in the same disastrous position, but I still think that if Wii U is dropped after this year, buyers will feel gypped. 

Like I said above, I think a Nov 2016 replacement would only fly if 2016 had a Wii U lineup on par with 2013 or 2014.

If 2015 is it's last year of proper support, and it's 2016 is like Wii's 2012 or Gamecube's 2006, they're in trouble.

I'm not going to create any unnecessary melodrama and just say 2017 or later for their next home console.

I'm looking forward to what they will offer us.

No chance the next console releases next year. If nintendo's smart they've already started work on the next smash brothers and mario kart to be released around launch of the next console. It will take more than 2 years to get them both ready.

I think that's doable. 

2013 had what? Mario 3D World, Pikmin 3, Wonderful 101, LEGO City, Wii Party U, Wii Fit U, Zelda: WWHD. 

Lets even assume the next Mario 3D game and Animal Crossing is off-limits from the Wii U for the "new hardware" (Fusion), you could still easily have something like --

Metroid U (Retro/NST?), Paper Mario U (IS), Diddy Kong Racing U (Monster Games/Retro), Pokken Fighters (Namco), SMT x Fire Emblem (Atlus), Mario Sports Game (Namco?), Hyrule Warriors 2 (Tecmo-Koei) etc. 

For 2016. 

That's not awful per se. GameCube's 2005 (equivalent year) was Geist, Star Fox Assault, Donkey Kong: Jungle Beat, Mario Party, Mario Baseball, Battallion Wars. Terrible. And 2006 was even worse, lol. Had zero impact on Wii sales. 

That's cos Wii enjoyed immense hype thanks to its breakthrough controller; the next Nintendo console after Wii U will be a much tougher sell if they end Wii U on a low note. The lineup you describe should be satisfactory though; like I say, as many key titles as 2013 or 2014 would get the job done.

Although MS put a lot of money and resources into it, a 4 year cycle contributed to make the first version of XB360 horribly buggy.
Risking to throw Ninty's reputation for reliability down the sink wouldn't be a good bargain.
Moreover, releasing so early and with the usual Ninty conservative approach to HW power and profitability could result in a half-assed console, but half-assed in HW power would be the smallest problem, the biggest one is the possibility of a half-assed concept, either wrong or not refined enough. With neither noticeable HW power increases nor big and desirable new concepts, features and HW innovations, people and devs would simply say about it "so what?" and the new console would end up catering again for just those 20-30M die-hard first party Ninty fans.

Nintendo Exclusives aren't enough , localize Fatal Frame 5 to the West & bring more third party exclusive like Bayonetta 2 !

It wouldn't be buggy if it's basically the same chip/architecture as the next Nintendo handheld. 

There won't be another traditional Nintendo console I don't think, I think people aren't getting that but it'll be fairly obvious in about 12-18 months if not sooner. 

They are shifting to a different model per Iwata's comments, more like the iPhone/iPad setup ... Apple doesn't care which of the two you buy, as long as you buy one you have access to the same apps and ecosystem and the performance/experience on both devices is relatively the same. 

This approach will let them sell a way for people to play all the Nintendo games at home on their TV if they want (if they don't then they can buy the handheld) and the device likely will be quite cheap and profitable from day one, unlike the Wii U. 

It could be reasonably more powerful than a Wii U too, two Apple A8 processors (the ones in the iPhone 6) put into a tiny box would outperform a Wii U I think, three would be a good deal more powerful and this is a 2014 component, Nintendo will likely be able to get something better than that for 2016. 

In this scenario though it doesn't really matter if the next 'console' only sells about 20-25 million for Nintendo. It would profitable all the way for one. For second there would also be another 55-70 million portable owners too ... so none of Nintendo's games would be stuck selling to only 20-25 million because every game could sell to both (same way iPhone/iPad apps can be sold to consumers on both devices in most cases). 

I cannot disagree with this.