Let me see...
2000 - Gameboy Advance
2002 - Nintendo Gamecube
2004- Nintendo DS
2006- Nintendo Wii
2011- Nintendo 3DS
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So my bet is that the next nintendo home console will be shown on E3 2012 and released worldwide in late 2013. Which means 2 years after the 3DS like it happened in past history.
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And i also bet that the control scheme of the next nintendo console will be an improved wii remote with the wii vitality sensor incorporated (but without the thing to put the finger... just by holding the remote it can read our heart beat). That is my explanation for the absense of wii vitality sensor on the wii...