What is interesting is that people often forget that Sony has said that technology similar to eyetoy is going to be a big part of PS3 out of the box.
So if Nintendo is trying to do something different, it's not like Sony isn't either. Microsoft, well, they are content with simply better graphics, lack of hard-drive etc... but of course, they'll offer 3 versions of their console.
What's also interesting, is that all rumors point to MS being first out of the gates, and that Nintendo and Sony will be releasing around the same time as one another.
So - if Nintendo utilizes some new revolutionary control/visual setup, and Sony tries the same thing (though possibly very different from what Nintendo does), and MS only provides a more powerful 'conventional' system - MS is going to be left out in the cold I think.
With Sony and Nintendo likely to offer some new form of machine, releasing at the same time, and after MS - Sony and Nintendo are both going to make MS look inferior. Now - that said - games rule - and they are what determines what people buy.