I don't see the Wii and Wii-U in similar positions at all. The consoles are different, the competition is different, and the market is different.
The Wii looked and felt very different from the get-go. Regardless whether or not the controllers lived up to the imagined potential, one could easily picture the possibilities, and Wii Sports was simply fun. There were great games in many genres, and it had some unique features like the Miis and the Virtual Console games. It was also relatively cheap. 3rd parties didn't flock to the Wii, but since dev costs were relatively low, you at least got some support. Most importantly, the Wii appealed to a huge range - traditional gamers had Marios, Metroids, Zeldas, Resident Evils... "New" gamers had a host of mini games, Dance Centrals, Cooking Mamas, etc.
Enter the Wii-U - there's nothing there traditional gamers couldn't get on 360 or PS3 (or haven't already played two years ago), and it'll have to compete with the 720 & PS4 soon. The "new" gamers that bought the Wii have no reason to buy the Wii-U, because it's a 'regular' console. And a complicated one at that. I've been playing games for 35 years and the Wii U's variety of menus, buttons, system updates, and crashes left me confused. I thought "how is Joe Consumer going to deal with this?" 3rd parties don't have any reason to put out Wii U versions. Gamers don't have much reason to buy one. It's going to take Nintendo longer to put out 1st party games, because it's a generation ahead of the Wii. I think their only hope is for some big hits in Japan to pick up sales, then maybe they can translate that over to increased dev support, more games, and then success in US & Europe. It's a long process, though, and the clock is ticking. I don't see it happening.
There's also a lot more pressure from mobile games, as well as Steam and FTP that makes the $60 game model tougher. I browsed the eShop channel and it was a little hard to swallow $20 downloads when I know i can pick up the same thing on Steam for cheaper, or just buy a $0.99 iOS game to kill some time.
Don't get me wrong, there are some good things about the Wii-U. I hope things turn around and we see some great games coming out. Realistically, though, I don't see it gathering much steam. We'll see what's announced at E3.