Now is the best time to pick up a Wii U, the console will have had all the major updates, a stream of decent games have begun rolling in, price cut,Zelda bundle etc. And contrary to popular belief, the 3rd party support is actually decent for a Nintendo console.
Watch dogs
Assassins Creed 4
COD ghosts
Batman Arkham origins
Sonic lost world
Rayman Legends
to name but a few.

Wii U is in trouble but it ain't dead like many people will lead you to believe. Just look at the holiday line-up it still has plenty of life in the system

both me and my brother have had one since day one.

I have own a total of 4 games during that time, all of which got little play and were sold on. My brother owned 1 game, which got little play time.

They have both gone months without even being turned on, my brother now wants to swap his for a PS Vita. Im gonna keep mine, as sooner or later a game will come out I really want, but there are only 2-3 games I can even conceive that I want for my Wii U.

Mario Kart 

A new Zelda (but not Wind Waker, I dont like the art style, and hope they go back to a more realistic art style for the new one)

A new Metroid Prime - which so far has not materialised or even been mentioned as a possible game

I really do think the Wii U is in trouble, there are few quality games and with the PS4 and XBox One right around the corner that pool of games is going to get smaller. Developers wont put there games on it while it has such a small user base, especially when said games are going to have been developed on more powerful machines which means to put it on the Wii U would require substanstial conscessions. 

The Wii U will depend heavily on its first party games, and even if some top quality ones come out it wont be enough to keep up with the other and persuade someone to buy the Wii U over the other consoles.

Umm...kinda?

In terms of threatening its immediate existence, no. The Wii U isn't in that kind of trouble. It would have compound its failure several times over before it reached the point of Nintendo pulling support for it. Even if it proves a commercial failure, Nintendo will probably ride it out to a somewhat respectable life cycle, if only because they've already invested so much in it.

With that said, the Wii U is effectively a niche system, appealing solely to people who will buy a system only for Nintendo games. Granted, as niches go that's the Grand Canyon, but if you have ambitions to play games made from people who are not Nintendo, you might consider a second console.

This coming Fall/Winter period is going to be key. For third parties, if the system doesn't start selling their games in respectable numbers, we might see what support it has been getting diminish further. For Nintendo, the fate of its system is in its mainstay franchises, and whether they sell systems.

For perspective, Nintendo is "estimating" sales of 9 million Wii U consoles for the fiscal year. Optimistically (very optimistically), let's say 8 million units between now and April.

> 6 million units: Good sign. The system is well on its way to recovery, as long as Nintendo paves the way to greater success.

3-6 million units: Could be better. System will probably need a fair bit of love from Nintendo to start selling smoothly, but a 100-200% increase in the install base will help Nintendo's bottom-line, if nothing else.

< 3 million units: Bad sign. This would be a point to actually start worrying.

I, personally, think the middle option is the most likely, but the higher threshold could easily be reached if Nintendo plays their cards right. 

WiiU will be fine, Cant wait for Metroid hope we get an F-Zero this time around as well, WiiU will end it's life with a great library of games.

At this point in time, that is the most logical decision.

It will probably be another GameCube or N64 like console in its appeal, but I enjoyed the GameCube and loved the N64, so there's no reason not to enjoy the Wii U. It will have some terrific Nintendo games on it, so if you're a Nintendo fan, it's nothing to really stress out about.

Nintendo hasn't had great third party support on a console for like 17+ years now so if anything this is just the norm by now, so why worry about that either.

It's fun to debate sales and company policy but it doesn't change my enjoyment of the console. I just hope Nintendo throws an F-Zero U or Wave Race U my way at some point and the release schedule is a bit more steady from here on out (droughts are going to be inevitable when its mainly one company supporting a console).

Yes it is, IF their upcoming 3rd party games Batman, Assassin Creed 4, COD Ghost, Just Dance 4, etc not selling well i think Nintendo not gonna have a "new" audience. And im really sure Mario 3D World will have a nice number.
I have WiiU and i have a hard time find a friend to play BOPS2 Online and MH3U, they are just blindfolded fanboy who just playing NSMBU and PIKMIN 3 even some of them didnt know how good or great game outside Nintendo games.
Oh one more thing, i didnt see Wonderfull 101 on the chart! where is it??

I've bought the console in febraury and so far I'm happy whith it. Mario Bros U is easily the best in the "new" series, plus Luigi U is a great add on. NintendoLand is surprisingly great, I've played it for more than 50h and I'm still not tired of it, expecially Metroid Blast multiplayer is great. Zombi U is an ok game.
To awnser your question, so far the WiiU had a bad start: if a price cut, Mario 3D Land, Donkey Kong and Mario Kart will not help than yes, it will be really in trouble.

The Call of Duty and Just Dance audiences can stay away from the Wii U, that's just fine and dandy with me, lol.