I would disagree with HC's assessment that they only flop has been the Virtua Boy. The 3DS is a slam dunk flop, they lowered the price less than six months after release, sales were so miserable that Nintendo earnings suffered, and not only that, but Nintendo themselves don't think that sales will pick up because they have lowered their earnings forecast twice. If that wasn't bad enough, they released that stupid right analog stick peripheral, other than headphones and an AC adapter, what peripheral has EVER been succesful on a handheld? Anyhow the hot rumor is that they are going to completely redisign the 3ds next year with the right analog stick integrated. I don't see how you think that isn't a flop.
The wii was great, but Nintendo never really supported it well from the get go, instead it allowed anybody that wanted to to make a game. So at the beginning there were a TON of wii games, but they were mostly garbage.
The president of Nintendo himself has said that the controller will be just that, a controller. It will have no tablet functionality to it. Its going to be similar in concept with the Vita, where you can transfer games from a handheld onto your console. Except the Vita is a standalone system that you can take anywhere, the controller will need to be coupled with the console.
I have said this before and will say it again, what is the market? Its not a next gen console in terms of capabilities, Nintendo's president pretty much says as much. Its only revolutionary thing is the touch screen controller, and if that is a big hit, Sony and MS will be a year away from making a competing peripheral.
As far as I can tell, the people most likely to buy are Nintendo fanboi's ( a shrinking cohort), or people that don't have a wii/xbox360/ps3. I think that is a small segment of the population.
Really though, its all about the games. If it has a strong library at launch exclusives, it could do well, if not, then its going to sink like a rock. That is part of the reason the 3ds sucks - no compelling games at launch.
I think Nintendo has really dropped the ball lately. The 3ds is a disaster, not making the wii HD was a big misstep, and this is the 25th anniversary of Zelda, a game that has pretty wide appeal, and there has been hardly any marketing push around that.
At this point in the game, I think Nintendo should just stop making hardware. What is great about Nintendo has always been the games. If they ported SMB to the iphone, it would sell like nothing you have ever seen before. Imagine what a six month exclusive for the next Zelda game would be worth to Sony or MS? I am sure their revenue would go through the roof.