Those who wish for Nintendo to become 3rd party are not realistic anyway.

Smarter fans hope for Nintendo to partner up with Sony or MS (not a buyout or merger, more like a lengthy contract 6-10 yr agreement), so that they would have influence on the console, and tech specs, online etc would not be an obstacle anymore.

Yup, one of few cases where I love them for being stubborn.

For instance was Mario Bros. released on Atari-machines:

Platform(s): Arcade, Famicom/NES, Commodore 64, Amstrad CPC, Apple II, Atari 2600, Atari 5200, Atari 7800, Virtual Console, Game Boy Advance (as secondary game in Super Mario Advance series), Nintendo GameCube (in Animal Crossing), ZX Spectrum, Game & Watch

http://en.wikipedia.org/wiki/Mario_Bros.

Also Donkey Kong, Donkey Kong Jr. and Popeye were released on non-Nintendo machines (I count Arcades as Nintendo-machines in that case).

Nintendo going third would really increase their financial performance on short term, but they will be totally limited by the current console generation.

Nintendo is good in creating inovation, limiting them anyway woud do no good for us.

That and their approach to mobile.

Not direct, but look at the controller for example. 90% of the PS4 and Xbox One controllers features were made mainstream by nintendo.

not true, sony invented the handles on controllers

That is why I stated 90%.

For me the only mistake was the Wii U Game Pad.

And not the concept, but the final design and use.

I wish it was something like this, not to stream games, but just as a complementar thing like the SmartGlass:

To manage inventory, minimap, settings, notifications, chats and so on. So we would kill the need of Screen HUD, and make it as clear as possible.

Even with erosion from the mobile sector, they should be able to sell 65-70 million of a hypothetical Fusion platform (home + portable variants).

That's enough for them to continue making a decent sized profit as long as the hardware is not stupidly designed.

Especially since they no longer will have a split where things like Mario 3D World can't be sold to 3DS owners, for instance, thus limiting it's profitability. Or in the past they could only sell like Wind Waker to the 20 million GameCube owners, but under the Fusion setup games like that would have access to all Nintendo hardware owners, not just the few who buy the console hardware.

Will they ever be as relevant to the overall gaming industry as they were in the 80s/90s again? Probably not. Those days are over, but they can still make some good money if they are smart in how they handle the Fusion concept. 

Affordable hardware that has smart chip design choices (ones that scale downwards in cost quickly) is a must next time. The 3DS and Wii U use too many propietary components and over rely on non-standard gimmicks like 3D screens and tablet controllers that drove their hardware price too high.