With news of Ubisoft (despite their terrible ports and delays, they have been Nintendo's most consistent 3rd party help in terms of quantity of big games) deciding WD will be the last mature game they put on Wii U (and imo based on the comment about just dance it means Nintendo will only receive kiddy games from them now), EA consistently not supporting Wii U, as well as a bunch of other companies, it is clear Nintendo doesn't have third party support anymore. Now what I'm curious about is if Nintendo even cares about this. Let me explain:

The rest of this year they will have a decent release pace of games for Wii U between first party and 2nd party collaborations. In 2015, however, as many of you have probably read by now the release schedule for Wii U is packed enough to release games once a game (BIG games, not rabbid's nonsense). So my question here is for the rest of this year and probably all of 2015 Nintendo will have amazing first party games, but they also have a lot of 2nd party games coming in, so I want to know what your thoughts are on Nintendo surviving on JUST 1st party and 2nd party games.

How many triple A 2nd party studios would they have to have working on Nintendo console platform exclusives in order to function in a successful and profitable way?

I think have 5 studios consistently making Nintendo console exclusives (they can still work on other games for other consoles too) would work. How many do you guys think and what would be your prefered stuios that you'd like to see become permanent 2nd party collaborators? 

As many as possible.
Third party support has effectively left the building, and they do not have enough first party studios to avoid game droughts.
They need to start buying up and/or cooperating with more outside developers. Especially Western ones, as their library is lacking the kind of games that draw the self-described "hardcore". (Generally Western males aged 12-30)

They need enough developers so that the gamers that choose the wiiU don't have to deal with such droughts. Its not gonna be easy but if you arent gonna play with third party games, u gotta give them something else

First they need to learn how to use their own better. Putting Nst to work on another mario vs DK game was a waste.

I expect it to receive more from UbiArt engine (something Ubisoft is surely not done milking).
Also one of those Final Fantasy spin-off that Square always make for nintendo consoles.

It would be great if Level-5 did something with them as a 2nd Party.
A Baten Kaitos with Namco would be great (and they could even use the gamepad for it)

They could also offer Treehouse to localize some of the japanese games, like those Dragon Quests...

Nintendo should create a special subsidiary that acts as the equivalent of a third-party publisher (but supporting only Nintendo systems, mobile, and PC - with the requirement that all games that they publish at least show up on one of the two Nintendo systems of the time). This subsidiary could operate somewhat independently, with its own identity and logo, for which a variety of types of games that Nintendo tends to shy away from can be published.

They could be given a budget for the first few years, with the goal being that profits would be fed back in until its self-sustaining, at which point it would begin paying dividends back to Nintendo. The subsidiary would have independence on things like advertising, choice of projects to fund, etc.

Currently-independent studios would be considered for acquisition by the publisher, based on the quality of their work and their interest in being able to work for Nintendo without being subject to the regular internal Nintendo restrictions.

By allowing the subsidiary to publish on PC/mobile, they would be able to expand their support base, while not allowing other consoles would ensure console exclusivity. Independence would mean that they'd be able to operate competitively with Nintendo on the systems themselves, but being a subsidiary would mean that they'd be required to support Nintendo systems.

If that's too complicated, then I say Nintendo should just go on an acquisition-spree, buy up a heap of currently-independent studios that make games that Nintendo doesn't currently make. I'd start with High Voltage Software, get them working on a new FPS, with oversight from Nintendo regarding art design and game structure to ensure top quality.