Do you make so many very specific predictions so that a few will be right out of many and then you can go back and say that you were correct in your prediction and that you're the "Gratest Preduckter" as stated in your sig? I say very specific because for this prediction, the two consoles have to be the same price for next Christmas, which isn't that when Halo 5 is supposed to be out? So if your prediction happens (which has a very good chance at happening for a time after Halo releases), it would be more about Halo than normal demand.
Would the Xbox 1 sell as much as the PS4 in the US if they were the same price? Maybe so, (Heck, it might sell as much anyway. I don't think so but it could.) but I doubt that is going to ever happen as long as Kinect is included.