I believe that in NA 360 isnt supply constrained yet. They did have supply problems in early to mid December, but not now. That is because they start air shipping units just manufactured in Since those were planned to arrive 2nd 1/2 of January by boat 360 will be supply constrained end of January and into February until units manufactured and shipped via boat this month arrive.
As for PS3 the problem I had with the supply constrained argument was that Sony used it for like the whole 1st half of the year. Im sorry that isnt possible unless Sony deliberatly stopped making PS3s because they were still being manufactured at a loss and they simply wanted some costs to drop before they started making them again. Still the sales never did jump when the supply was fixed. Same with the 360 this year if sales dont jump back up (they havent dropped yet) after the constraint is fixed then the supply problem wasnt a problem at all.
Its libraries that sell systems not a single game.