The demand for a next gen isn't the same in all countries...
If five of your friends already have a PS4 and no one owns an Xbox One, imagine if you were to buy one of them just for Fifa or Cod (here in Norway this is pretty common). You would normally go with the one your (fifa and cod playing) friends have. The delay to next year is going to hurt them, I am however not sure if this delay (from spring or so to christmas) is going to hurt them that much. Releasing closely to the christmas isn't a bad idea.