Does anyone agree with me that it's mostly lack of games that affects sales instead of games? Sure, in the beginning games matter more but as the generation goes on, they become less and less important. Right now the PS3 has no huge exclusives in Japan but FFXIII will be one. I'm not expecting it to give a huge boost but it will definitely have a visible effect. And in the west... Well, we have games already; there aren't many things that could change the situation all by themselves. And I don't think Gran Turismo is a system-seller.
Oh, and about this mathematics - big numbers aren't the same as practically impossible numbers. Right now it's getting pretty unlikely for PS3 defeat 360 but it's far from impossible. Price is a huge factor at the moment - if a $400 system can almost keep up with a $199/$269 system (sorry, not sure about 360's current price), there's definitely MUCH room for growth. And did I mention brand name yet? Even if Xbox is bigger than ever, PlayStation is still bigger. Well, in that sense regions are very important I must say.