Really, even if it only sells as well as the EyeToy, that's nothing to scoff at. I mean if the Move (just speaking of the Move controller) can sell over 10 mil units, that would be a big success. Then, you have to think of all the Navs people would most likely buy. They'd be making some serious dough off of that. But, I feel it may surpass the EyeToy's success, especially considering it can offer a more core gaming experience, as well as being better supported by first and third parties.
As far as day one sales go, I don't how big they'll be, but Sony will at least have 2 Moves and 2 Navs purchased by me. 







