Im not sure if its that important for Sony to beat the X360 in NA.
Most game dev studios are NA based and they are looking at that market to decide about future developments. Japan doesn't matter to them at all - and only a few franchises are important for Europe, like Gran Turismo and Fifa.
Last place in NA is pretty close to becoming the least important player.
Selling 100-150k less consoles per month in NA than the main competition is far from as big of a deal as many portray it to be.
As long as you don't look at the ~8 million console lead that the X360 has and realize that Sony would have to keep selling at least 250K more than MS just to catch up to them, well, it really isn't such a big deal then...