Let's ask this question after E3 and how the sales look after a year.

It's not going to fail. It still has the die-hard faithful who bought the Wii U and it should have all the people who still want a handheld gaming system (though that number will probably continue to shrink). It will have the Japanese handheld support that went to the 3DS and it might even have the support that went to the PSP/Vita, which was substantial (though Nintendo probably won't co-fund nearly as many games as Sony did).

The Switch will make money for Nintendo and it should have an install base near the range of the 3DS.

Now, that being said, the Switch is supposedly taking over for both handhelds and home consoles, so it needs to surpass the 3DS hardware totals and blow away the software totals or else it will represent contraction rather than growth.

Wii had a bad third-party support too but sold very good.

You just answer your own question contradicting yourself. If "everyone with a job" can afford more than one console, it means people without a job can't, which are more than just 12 years old.

How do these camel balls taste?

Afford?  With millions of people struggling to pay the rent or put food on the table?  Seriously?  Many working adults have far greater priorities with their money.

What are the odds Nogamez is between 16-23 without a real career, a long-term relationship, and especially children?

Even if you have all the money in the world, you might not have enough free time to justify buying another console that you'll rarely, if ever play.

Failure is a relative term... some say Gamecube was a failure...but was it? It was no PS2, got outsold by Xbox by a few million, but Nintendo was only raking in cash. That's how I think Switch will play out. Nintendo didn't start getting into "they're doomed" territory until they started selling consoles at a loss or just didn't have any decent games out.

I'm not saying Switch doesn't need 3rd party support, I'm saying the 3rd party support it needs has to be very selective and possible. So, mostly Japanese 3rd parties will be able to support Switch no problem. But anybody expecting the Switch to be able to run Red Dead 2, or ME:A, etc. on such a small form factor is quite frankly insane. I mean, the games could theoretically run however there'd be huge drawbacks.

The difference for Switch is that it's a totally new product, it can't go down in price like PS4 and Xbox One, it's new tech. It is fully portable, something the PS4 and Xbox One can't say. That, itself, is a huge selling point. And last but not least...it will have POKEMON. It's already guaranteed that it'll outsell Wii U while eventually turning a profit on hardware and software at the same point in time.

Switch also benefits from a shared library. I know we don't see it now, but Switch, even without huge AAA western support, will have a ton of content. With Virtual console, and all of Nintendo's teams working on one device to produce Fire Emblem, Mario, Zelda, Donkey Kong, Metroid, Pikmin, Kirby, Smash, Mario Kart, etc., along with help from Japanese 3rd parties whose games don't need power to be developed well, i.e. Sega, Level 5, Tokyo RPG Factory, Capcom, Square Enix, etc. Switch will be a well supported device. I think we're jumping to conclusions too early on what is essentially a "soft launch".

It will do almost the same, with or without third party support.
Id say switch with third party would sell only 5 Million more than switch without third party