I think people need to chill the hell out with the 'X1' or 'PS4' domination threads based on short-term rankings. It's an epidemic lately. If this thread is a parody of the numerous X1 threads then sorry in advance.
We will find out.
All we know for sure for now : both are doing fantastic.
My gut feeling : X1 is understocked, and that will hurt MS a bit. Sony looks to have SERIOUSLY prepared mass stock for the BF to Xmas weeks.