It's important to note that this has been Microsoft's MO for some time now: they enter a new market, spend loads of dough, and gradually accrue market share. Then, they tie that new product in with their old ones, and effectively solidify their hold.
The easiest example of this is Internet Explorer. Many people may not remember the glory days of Netscape, but IE gradually eroded market share thanks to direct pushes from Microsoft (some pretty shady ones, at that). Slowly but surely.
I'm not convinced the same is happening in Japan, but it follows the same model. As the Source said, it's likely that the 360 will double Microsoft's market share, and I suspect the 720 will increase even further, unless they simply stop making RPGs (Blue Dragon 2 is already in development).
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