Nintendo has just annunciated that they are planning to introduce the Wii successor next year. No information regarding to the system have been mentioned. Nintendo only announced that they will show a playable model of the new system and will announce more specifications during the 2011 E3 expo, which will be held June 7-9, 2011, in Los Angeles.
This is the official statement that was announced by Nintendo regarding to this new system that they are planning to release next year:
April 25, 2011
To whom it may concern:
Re: Wii’s Successor System
Nintendo Co., Ltd. has decided to launch in 2012 a system to succeed Wii, which the company has sold 86.01 million units on a consolidated shipment basis between its launch in 2006 and the end of March 2011.
We will show a playable model of the new system and announce more specifications at the E3 Expo, which will be held June 7-9, 2011, in Los Angeles.
Sales of this new system have not been included in the financial forecasts announced today for the fiscal term ending March 2012.
[Source: Nintendo [PDF]]