Natal has more of a chance of taking off than Sony's Wand does. I'm also not crossing my fingers that Natal fails or anything, if you read my post properly you would have seen that I was just stating possible scenarios.
In my mind Natal is Microsoft's strategy to keep the sales pace of the 360 at the level it's at now for longer. Which is why the PS3 has a chance of catching up if Natal fails and the 360's sales begin to slow down but won't be able to if Natal does really well.