I think it will do well over time and have legs. With the recent announcement that Lost Odyssey is arriving this holiday season, games like Eternal Sonata and BD might sputter for a bit but should sell decently into next year on the heels of Lost Odyssey (you can bet MS is going to advertise the crap out of that game).
BD should also get another shot in the arm in Japan when LO releases there... I'm sure that 360 sales will spike again and many of those people will pick up both BD and LO at the same time.

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