Maybe Nintendo will finally realize that 3rd parties simply will not give full support and wont sell well on there consoles.

N64-most powerful, poor support

GC-decent multiplat support, horrible multiplat sales

Wii-market leader, poor support

Wii U-first on market, poor support/poor sales

Nintendo needs to realize all they need to do is release affordable hardware (ideally $199 at launch) sold at a profit with a steady stream of 1st/2nd party software and they will be fine. If they do this it doesnt matter if the hardware only sells at Wii U levels because they are still making money and the big Nintendo franchises will still sell well.

Even on a lifetime install base of 15 million (currently what Wii U is tracking) 2D/3D Mario, Mario Kart, Smash Bros can each sell around 5 million, Donkey Kong, Zelda, Animal Crossing can sell around 3 million and Pikmin, Metroid, Kirby, among others can sell over 1 million. Gamecube, Nintendo 64, and Wii U are proof that Nintendo games dont require a huge install base in order to sell well.

It's because Nintendo don't activley court third partys as well as Sony and MS, who both have departments and money dedicated to securing 3rd party content and 3rd party exclusive content, they do this in the way of partnerships, incentives, joint marketing not just by making themselves the publisher.

I love my 3DS but Nintendo need to wake up.

I just got a wiiu for the nintendo games. My ps4 is for the multiplatforms.

I actually don't think it's this simple. 

There are a few problems with your arguements. One N64/GameCube budgets are a fraction of Wii U budgets, and presumably you want another Nintendo console, which will likely be in the PS4-range of chipset ... which will cost even more money. 

Having just a 20 million (or even 30 million-ish) userbase simply isn't enough when development costs keep rising. 

The other point is the Nintendo audience has eroded a lot in the last 15 years even from the N64 days. On the N64 things like Wave Race and 1080 Snowboarding and NBA Courtside and Turok could sell more than 1 million copies WW easily, and games like Star Fox 64, GoldenEye, etc. cleared 4+ million.

Today's Nintendo audience quite frankly is a lot more narrow in their software choices. They've lost a lot of Nintendo fans that bought the above games to Sony/MS and have been left with a very tunnel vision focused audience that buys primarily things with just Mario in them. Even for Nintendo these days anything else beyond a narrow formula is a pretty tough go. 

I do buy  Nintendo consoles because of Nintendo games but it does not mean I will only buy their games.

My current Wii-U library is :

Nintendo : Nintendo Land, Pikimin 3, SM3DW, DKC:TF, Wonderful 101

3rd Party : Lego City Undercover, Zombi-U, AC:III, Darksiders II, COD:Ghost

However I agree with the OP, the "mass" Nintendo buyers are the family/party gamers that will only care about Nintendo games. That is why 3rd party games sell so poorly exceptiosn being party games (Dance Dance, etc...) or family games (lego, ...).

thats why i bought my 3ds and wii u.

ya wa hoo

True, which is why their console is suffering. It has no appeal to you if you're not in this group.

I dont care what type of chipset it has, Wii U could be right in the middle of Wii and 360 in terms of power for all I care.

Ur right that certain games did have major declines from N64 to GC, mostly sports/racing/shooters which the competition thrives at, Nintendo needs to experiment with these genres again and try to find an audience for them. Star Fox is a bad example tho, Adventures was a spinoff and Assault was mediocre and released late in its life, both still sold over 1 million each.

There are also many series that sell rather consistantly on Nintendo consoles regardless of install base. Outside of the original and the first Prime, Metroid sells roughly 1.5 million, same with Kirby with a few exceptions. Zelda/Donkey Kong/Animal Crossing have never sold under 3 million, Mario Party/Paper Mario have never sold under 1 million. Mario platformers, Mario Kart, Smash Bros have never sold under 5 million.

Just release affordable hardware sold at a profit with a steady stream of software and ur fine.

yeah... this excuse.

Self fulfilling prophecy.
Make games I want to buy and you'll make the sales.