Honestly though this is a bit of a myth, the GameCube and Wii technically may have had 5-6 year "lifespans", but Nintendo left both of those systems to die long before they hit the 5-6 year mark. 

Nintendo basically gave up on the GameCube by 2004, and they've done almost nothing for the Wii in 2011 and 2012. Releasing one Zelda game doesn't cut it. 

Personally I think Nintendo damaged the Wii brand much moreso by just leaving it out there with no software support rather than if they had cut it's lifespan shorter or released a Wii HD around 2010 or so. 

If Wii U never does take off. They'll take whatever profit they can make on the hardware and games and then work on a new console.

They'll go back to manufacturing playing Cards. That's where the money is, especially considering the market is hot right now.

probably a wireless handheld device which can act on it's own with a wireless dongle to plug in to the TV and play there.. and they will call it Game Boy TV

In the sixth year, certainly it's true software dries up as the console companies gear up for the next cycle and try to finish up launch titles in time, but in the fifth year software support is usually still pretty decent.  If I remember correctly, GameCube had four or five Mario games come in 2005 alone, as well as a Fire Emblem.  Wii had Skyward Sword, Wii Play 2, and Mario Mix sports or whatever it was called.   So, that's fairly decent for a console's last year without a successor. 

If they were to make systems every four years, then support would dry up even faster, and after the fourth year there would be nothing, instead of it drying up after the fifth year.  That would just be way too soon.  People invest in a console because they assume they're getting five years worth of games.  I don't know if I'd buy a Wii U if support was already scheduled to be finished in 2016.

The N64 had Perfect Dark, Conker's Bad Fur Day, Banjo-Tooie, Paper Mario, Zelda: Majora's Mask, several Mario Party games, Pokemon Stadium 1/2, Star Wars: Battle for Naboo, Mickey's Speedway, NBA Courtside 2, Excitebike 64, Ridge Racer 64, Animal Forest (Japan), and Sin & Punishment (Japan) etc. its last two years from Nintendo directly. 

*That* is support. The GCN and Wii were abandoned and left for dead by Nintendo after year 4. 

Doesn´t matter that much if they win the gen, what matters is if they are making a profit with the WIIU. Let us say that they make 10 dollars in profit with each WIIU sold, and they manage to sell 20 million lifetime, that´s 200 million dollars profit, aside the software.

The Nintendo fans will buy the console, soonner or later, I am sure.

Not bad at all.

What is killing SONY is not that MS is a little ahead, is the fact that they sold PS3 at loss for so long. So, you DO NOT HAVE TO WIN any gen to be healthy, you only have to turn a decent profiit, that´s it.

Has Kirai should have this in mind: is not about anihilate the oponents, it is about staying alive, be the herbivores of game industry, that is the secret.

You know, if my neighboor have more money than me, it doesn´t mean I am going to die, as long as I live a happy and cool life, I don´t give a crap about if the rest of the world is happier or richer.

The same with the big three, if they turn a profit, they are fine, regardless of how the other two are doing.

That is why I say: whatever happens, Nintendo will be ok.

Well Nintendo doesn't own Rare anymore, so without Banjo, Perfect Dark, Conker, and Mickey Speedway that's a far less-impressive lineup.   I'll give you Majora's Mask and Paper Mario, though.  Two of Nintendo's finest games.

Well, if WiiU doesn't perform as Nintendo wants, I think that Nintendo would wait the usual 5 years or so to launch a new console, otherwise it could be seen as a betrayal to their WiiU users like SEGA did with the early move from the Saturn to the Dreamcast.

Besides, even if it doesn't perform well, it's better to continue selling a product that gives them money than launching too early a new device that will make them lose money without knowing how well it will be recieved.

I also think that they will ditch the Wii brand and, like many have suggested, the integration of the home and handheld hardware divisions could be an indication that Nintendo's new consoles could be a home console with a fully capable handheld as a controller or something like that (but then, this machine would be expensive).

Another thing to consider is third party support. If WiiU has it, Nintendo's next console may try to follow WiiU steps in that regard, but if WiiU fails again to get their support, Nintendo could (should?) reconsider it altogether and develop a machine for their exclusive needs and games, allowing third parties to come along and develop for it if they want but without making any compromise in specs or special features to cater them.

If the Wii U manages to sell 20 Million+ like the GameCube did, they will likely just release another System in 2017 and move on.

If Wii U fails completely as in pulls a Saturn or Dreamcast and manages only 8-10 Million lifetime, I'd assume that Nintendo would stop making Home Consoles, and focus on their Handhelds. I personally don't think that would ever happen though. 

Plus, unlike back in 2001, a lot of people buy more than 1 System per gen. PS2 completely dominated while the GC & XB were left with only the Deepest and most dedicated fans. Wii wasn't ALL Casuals. People had a PS3 + Wii or 360 + Wii. Sure, it wasn't their main System but it was their 2ndary. 

Once the Wii U expands its library, it will start selling fine IMO. Also, not just Mario or Zelda. I'm talking other games too like Kirby, Animal Crossing, Pikmin, Starfox, The Wonderful 101 and many more. Sure they don't sell AMAZING on their own but they still have a following and can still help sell Systems. I am a believer of library's selling Systems not individual games. I could be wrong but I expect Wii U to also be the 2ndary System for a lot of people because of the exclusives. Orbis + Wii U or Durango + Wii U is likely IMO.