To put it simply, Nintendo isn't SEGA. When you are a company like Nintendo, as rich as Nintendo, as successful as Nintendo, if you have 31+ franchises like Nintendo, if you have a loyal fanbase like Nintendo, one console failure won't damn you.
SEGA failed because they didn't have the $$$, they had few franchises that sold, ie. Sonic Adventure and Phantasy Star, maybe Skies of Arcadia and Evolution II but that was it. SEGA didn't have the backing that Nintendo has always had. The Wii U will be successful soon enough. Nintendo just needs to lower the price by 2014 and market it much better. I haven't seen such horrible marketing by Nintendo... EVER. If they play all the right cards Nintendo will beat out XBone easily but, not sure if PS4 will be beat so easily. Sony wasn't the ones converting potential Wii U buyers to XBone buyers. Think about it.