The Wii U has already been released in the United States and despite complaints that the system will be a failure, has sold 400,000 units in the 8 days it has been out. In both the United States and the United Kingdom, Wii U's predecessor, the Wii, has been the top seller in the console wars, with Xbox 360 second and PS3 trailing last.
Modern gaming is split into two sections nowadays - the "gamers games", which will involve either rehashes or sequels of classic games, or be general modern "hardcore games", such as Assassins Creed, Mass Effect, Dead Space, Bioshock, Portal, to name very few. The rehash games are often developed by Nintendo, such as Mario and Zelda, but third party companies like Sega and Capcom develop these too. The other section, are the "casual games". These games can be considered system sellers, as they are played by casual gamers. People who had no interest in video games ended up purchasing Xbox's or PS3's to play games like Call of Duty or Fifa (these games are well known to be inferior on the Wii due to the gimmicky controls and low-resolution graphics). These "casual gamers" usually have no intent on playing games like Bioshock or Mass Effect, as it was never their intention to play what can be considered proper video games. The "hardcore games" I am referring to are mostly on the Xbox and PS3 rather than the Wii, which was another way the Xbox and PS3 were sold as they owned the games.
In England, despite the Wii being sold more than the Xbox or PS3 due to the whole family appeal, a lot of people who play games in the country are the "casual gamers". Playing Fifa is like a religion to some, and is one of the only games some people will play for the console. It is considered embarassing to own a Wii in England as it's seen as the "baby" console due to family-friendly advertising and a glut of casual games on shelves. The nerds are often associated with the Wii as well as it owns the Mario, Zelda, Metroid, and other first party games, which is true - a lot of people who play these games played them when they were only first around in the 80's and 90's. Therefore, Nintendo has alienated the "casual gamer", who can be considered the main consumer of the industry.
Nintendo has vowed to "lure the hardcore gamer back" with the Wii U, and they have done this with less casual, family orientated adverts, and instead focuses on both the first party games, and the third party games, which are actually quite strong. For example, games like Mass Effect, Tekken, Batman, and Assassins Creed which used to be exclusive to the Xbox and PS3, are now on the Wii U. This could be crucial to help the Wii U sell units, as not only do they have their first party games, they now have the popular hardcore third party games.
The Wii U comes, as like every other console, a new console, and in true Nintendo fashion tries to stay as innovative as possible. It's not quite as futuristic as the motion controls of the Wii Remote, but the rise of tablet and mobile gaming may prove to be useful to Nintendo due to the Gamepads similarity.
While the United States is more open about Nintendo gaming, and will possibly be even more so thanks to the inclusion of third party games, it's still going to be hard to convince the casual gamer of England to buy the Wii U. It's still not going to be the essential purchase for the gamer only interested in Fifa or Call of Duty. It certainly won't sell as well as the Wii did due to the lack of futuristic innovation and family appeal, but I disagree with the popular doubt (even supported by Nolan Bushnell, creator of Pong) that the Wii U will be the "end of an era" for Nintendo.