uh because ps3/360 have an install base of over 160 million, and devs want to develope on hardware thats way more powerful then current gen. then you have some of the biggest franshises not selling good on wiiu, like COD,AC4 and batman, when third party's see this they think they dont have a chance.

Have we not discussed this ad nauseam already? There is a multitude of reasons, Nintendo ignoring 3rd parties during the development of the system, low console sales, hardware not up to par with other next gen consoles, and for the most part 3rd party games don't sell too well on the system.

Because even if Wii U were as powerful as PS4 and got the same multiplats, the average hardcore gamer would still get the games for the platform that their friends own. And at this point Nintendo doesn't exactly have the reputation of a console maker that lets the cool guys gather to play online games and talk shit to those who just can't keep up with their performance. Nor are they known for attracting the kind of consumer that enjoys bragging about playing the console version of a game at its highest available performance more than he would enjoy actually playing the game.

Nintendo's past has really hurt their brand image in this regard which in turn greatly has hurt the sales potential of third party titles on their platforms, and without some serious effort I fail to see how this could change anytime soon.

I don't think there's much Nintendo can do about third parties at this point. However, this is what I'd plan for the next generation...

1) Make your next console's power more in line with a next gen console instead of feeling like the most powerful last gen console.

2) Embrace the mainstream. Stop trying to be so different every generation. A lot of good can come from doing things your competitors are doing.

3) Shed the old Nintendo image. Create a new image of a more mature Nintendo. Make new and grittier franchises. Gamers grew up and are more diverse. You need to attract those different groups. Look, sound, and just simply feel like a company out to prove something. Right now Nintendo went from being obviously complacent to looking defeated. Bring the fire back.

4) Open up dialogue early with third parties and be flexible. Tell them what you're doing with this new device, what your plans are for a new Nintendo, and welcome whatever they send your way.

5) Buy partnerships. Get in bed with third parties. Market the hell out of their games. Make gamers take note and this will give more third parties confidence in backing you.

That's pretty much all I can think of. If Nintendo wants third party backing in the future this is probably what they have to do now.

buy third party games

it cant. either discontinue it and release a new system with higher specs than ps4 in 2015 or ride out the low sales until 2016

It wouldn't have been like that had:

EA not dropped support out of butthurt.

Sega not taken away the wii u exclusive content for Aliens:colonial marines.

And Ubisoft not have ported and delayed rayman legends. 

the only way i see is nintendo saying to thirds:
ok ubisoft, u can do a 2d mario with ubiart for wii u.
ok, warner, a exclusive screblenaults and a lego game.
ok, rockstar, want to work with a sandbox metroid? ok, now u can.
ea, mario strikers, are u on?

That game was labeled as wii u's exclusive for a long time, it came afer a long drought of games and it awas competing against GTAV on other consoles. Yet, the ps3 port sold more.  IMHO Rayman's performance on the wii u was mediocre at best.

http://www.vgchartz.com/gamedb/?name=&publisher=&platform=WiiU&genre=&minSales=0&results=200

That's why.