I just think its too early to tell right now. Let's wait until more GAMES are unveiled later this year.

If all comes to worse and the WiiU somehow ends up sucking, it will still be successful simply because of the success of the Wii.

Zelda, Smash Bros, Mario Kart do sell consoles like N64 and Gamecube proved. But they are not enough to make it sell like hotcakes, that's what Nintendogs, Animal Crossing, etc. and third party games are for.

@OP

If those don't do the trick, then Metroid:Prime HD certainly will.

Zelda and Smash Bros are certainly not enough to sell the Wii U, but you're flat out wrong if you think Mario Kart won't help its sales. Sure, Gamecube and N64 had it too, but, at that point, MK's popularity was at SSB's level, but, at this point, Mario Kart, with in the ballpark of 40 million games sold this generation alone, is one of the most popular gaming IPs in history. It also helped sell the Wii, for the record, since it helped the DS audience approach the Wii and will most likely do the same for the 3DS and Wii U, but in a far higher amount since the brand popularity has increased several times over with the Wii. On top of that, it has another immense 40m+ this generation brand that it didn't have with the GC and N64; it's called Super Mario Bros.
Also, while it's true that the Wii was the largest, most unlikely coincidence ever, since motion exploded and MS and Sony made fools of themselves at the same time, Wii U doesn't need to be. They had nothing but an unreliable and miniscule base back then, yet now Nintendo is probably one of the most accepted family entertainment brands ever and their audience is probably impatiently awaiting the next console.
Your next paragraphs are just opinion so I won't bother, but I find it difficult to believe that the userbase that bought well over hundred million Mario games this generation and the same for the Wii series will let a console with Wii in its name sell less than 60 million. Your hypothesis of N64-esque sales seems downright amusing.

I don't want to imply that Nintendo fully predicted the success of the Wii, but I do think that they anticipated the "meltdown" of Sony and built the Wii around its eventual failure ...

Sony, Microsoft and Nintendo have far more information about what their competition is doing than the average gamer does. Between outright leaks and more indirect rumours, long before a project is demonstrated to the public their competition (probably) has a fairly good idea of what it is. With that said, with the PS3 Sony was broadcasting the technology they were using and the features the PS3 was going to have years before it was going to be released, and with Nintendo's knowledge they were probably expecting Sony to be forced to release a $500+ console when they decided to go forward with the Wii.

LOL! I love the Dreamcast comparisons people are making in regards to the Wii U... are you implying that the system will be released by a company in serious financial troubles, with virtually no 3rd party support, and that it will have the plug pulled on it less than 18 months after launch?

Just because the Wii U is viewed as a "half-step" between console generations, that =/= the Dreamcast. The Dreamcast was an N64 with discs instead of carts, memory cards with a screen on them, and even worse 3rd party support.

This is just silly.

Firstly, we only know a very small proportion of the Wii U's gaming library. Obviously it won't just be Kirby, Mario and Zelda.

Secondly, Nintendo can't hope to replicate the Wii's success with the Wii U. If they went the same route, people would think "what's the benefit in this? I can do all of this with my Wii!" and it wouldn't sell to that audience at all. The controller screen is an interesting idea, and it could work very well. It will certainly work better than just duct taping together two Wiis.

Thirdly, Sega was in a mess when the DreamCast launched, and they were up against competitors in a very strong position with enormous amounts of money to spend.

Nintendo haven't showed the killer ap yet because they don't want to give Sony an opportunity to copy it with vita. Nintendo only release hardware when the current hardware can no longer realise Miyamoto's genius. Wiimote was released with the GameCube slim for Wii Sports, BB for Wii Fit, Wheel for Mario Kart, M+ for WSR and 3DS for Steel Diver and Face Raiders.

Why would you doubt Nintendo?

OT: Wii Sports U Resort Online HD isn't going to sell WiiU either, neither is Wii Fit Plus U Online HD or Brain Training DSiXXXXL or Nintendolphins.

Obviously. Games don't sell consoles...stores and online retailers do Hardy-har-har!!