Gamers, get those credit cards ready: another console war is coming. On May 21, Microsoft is likely to announce a successor to the Xbox 360, a console that's sold 76 million units since its 2005 debut. But between Sony's splashy PlayStation 4 announcement this February, and the ubiquity of versatile, affordable smartphones and tablets, Microsoft may face an uphill battle. Here's what the company needs to do to keep competitors at arm's-length.
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