Thats because the gaming business is the only business that Nintendo has...

That may be true but Nintendo supported the Gamecube from the beginning to the end (Just like the wiiU) and they released quite a nice amout of exclusives! Heck, the GC ended with Twilight Princess, one of the best Zelda games out there! Vs, you look at Sony... The number of games they have been releasing for the vita have been absymal and not to mention, the Vita got bearly 30 seconds of screentime during e3... And not only that, but games like FF Type 0, which fans wanted for the vita, are coming to the ps4 instead... So, you have that, along with a whole list of other reasons such as Sony going from marketing it as a dedicated handheld to what is now a companion device to a ps4 and even making jokes about its non-existence pretty much goes to show how little they care about the device...

So, as you can see, The GC and the Vita are in different situtions and considering that even the wiiU is tracking to over take it by either the end of this year or at its worst, by the end of 2015... Yea, I don't see it happening unless they make it as their smartphone or something

2015 will be a great year for gaming, here are my forecasts, which are really just guesses, I can be wrong:

January:
- No big releases, some cool quirky indies and AA games, console sales will be solid, but not that great.
- USA will continue to bomb Syria and to broadcast fake ISIS videos to justify it, this will last through january.
- The Ebola (man made) virus will continue to rise and kill, death toll will be around 100k-200k worldwide.
- Using the Ebola virus and ISIS as an excuse, America will invade Syria with ground troops and take away more liberties from its own population. Militarization of the police will take a step up.
- Gun control measures take away all citizens´s firearms in the US.

February 2015:
- Some big games will come out, like Dying Light. Witcher 3 will be the criitical darling of the month, gamers will responde with enthusiasm, sales for this will be in the millions (probably 3).
- Barack Obama will intensify his gun control policies with more fake school shootings and CIA staged events. Hollywood will support him.
- Syria is invaded.
- USA now focus on Iran, some lies about the country are spread.
- In Brazil, Aécio Neves starts a unninspired mandate as president. Water droghts in my country cause chaos and hunger, riots start.

- March:
- Some cool games are released, but sales start to suffer as America goes into the worst economic crysis from its history.
- The CIA spread lies about Russia and creates annother tension between the countries.

- April.
Obama starts to persecute christian and free thinkers. New Age One World religion becomes stronger as fake staged terrorists actions are blamed on christians.
- In Brazil, martial law is issued due to the lack of water.
- Ebola death toll is on the 3 million mark, the epidemic is no longer manageable.
- US starts to kill on sight people with Ebola symptoms. Other countries follow the example. Around 50-100 million people are executed with flu and other diseases. Only 1% of the dead really had Ebola.
- Tensions between US and Russia rise.
- China, Brazil and India declare that they will no longer use the US dollar as a standart for trannsactions, Wall Street crashes.


May:
- Video game sales go downhill, the industry halts development in fear.
- First direct attack from US to Russia.
- World War 3 starts.
- Obama start to execute people in riots and forbid all religious congregations to "prevent terrorism".
- Ebola virus mutates to a rabbies like disease, turning sick people into raging monsters that are shot on sight.

June:
- No one is playing video games anymore, mothers are crying, children are starving, martial law is a common place thing in all countries.
- Ebola death toll is in the hundreds of millions, most of them are just executions blamed on the disease.
- Obama nukes Russia with more than 100 nuclear missiles without Congress authorization, death toll can not be estimated, but people fear it could be around 90% of russian population.
- In fear, the world stops and do not react to the nuclear attacks. Obama is the unnoficial king of the world.

July.
- Americans are killed in the thousands by Obama´s police, militas fail to react cause gun control took all their guns.
- Christians are executed, many just renounce their faith in public.
- A digital eletronic mark is made on all the people to distribute rations and water all around the world.

August.
- Obama declares to be greater than god and states that there is no god but him.
- All around the world people are forced to worship New Age idols.
- Death toll for Ebola and WW3 is 2 billion.
- In the new regime, video games are sold to the population with the mark of Obama for low prices.
- Batman Arkhan Knight and FF15 are released with great praise.

- September.
- Uncharted 4 and Halo 5 top the charts, Zelda U is delayed.
- Obama kills two prophets that opposed his regime. Christian executions are broadcat through Youtube.

- October:
- Obama is shot, but ressurects as a transhuman cyborg. Declares that is god and immortal (again).
- Zelda U is released. "Best Zelda in years" says IGN.
- CNN reports states that no christians are left in America. In reality, millions still worship Jesus Chist and God in secret.
- One World Religion is stablished, the Vatican supports it. All bibles are outlawed and confiscated.
- Youtube users that do not support Obama are executed.

- November.
- Rumours about a Nintendo new console appear.
- Sony releases VR plataform to little fanfarre.
- MS releases Gears of War One.
- Demonic possession in a all time high, government says it is schizophrenia.
- Ebola misteriously disapears as the mark of Obama is now a worldwide prerequisite.

- December:
- Nintendo releases a Quality of Life casual console, sales reach 2 million worldwide.
- Sony announces partnership with Rockstar to release Christian Hunter, a christian killer new age open world simulator. Rumours that the game is exclusive to PS4 cause uproar.
- MS announces that Christian Hunter beta is free on Xbox One, gamers get happy.
- Obamacare become a worldwide program, alteration of DNA is now mandatory to "prevent diseases". Those that do not take the treatment are killed.
- Squaresoft releases Final Fantasy 7 HD remake to critical praise.

Something like that...

They could goes handheld only

What this had to do with releasing another handheld or not

And have a single point of Failure? Any company with a successful business knows that if you only have one product thats making your company successful, that is not a sustainable business because if it fails, then you will be losing money for a very long time so if they go handheld only, the risk will be very high and it would be a terrible business move which I doubt they will make... Sony can go console only cause Sony can make money from their other devisions as well as the gaming devision so if their gaming devision fails, its not as big of a deal but if Nintendo goes handheld only and it fails, they Nintendo will make zero profit for the next 5 years...

Well, if they clearly don't care about their current handheld and they gave up so easily after one average holiday, then they clearly don't care about the handheld space at all hence why they would rather put their money somewhere else

No Nintendo handheled fail and will never fail

And how do you know that? If you havn't noticed it yet, the handheld is a shrinking market do to the large popularity of smartphones... So, the increasing competition and the large growth and popularity of smartphones only raises the risk of Nintendo handhelds being a flop at some point