The more I hear about Natal and Sony’s wand, the more I am reminded of the Sega 32x and Sega CD. Both were late-generation add-ons that the dedicated fanbase of the Sega Genesis heavily anticipated, and were praised because of how they “Enhanced” the possibilities of the system. Unfortunately, they were add-ons that were overly expensive that few publishers supported and they did not sell well; and their failure hurt the reputation of Sega, which then destroyed all remaining respect with the release of an amazingly expensive unsupported system (the Saturn).
I personally won’t be surprised if Nintendo was looking at add-ons like the 32x and Sega CD when they decided that it was a bad idea to release an add-on for the Gamecube; and decided to make the Wii as their system for this generation.