For the twentieth month in a row, the Xbox is the top selling console. With sales numbers at 193,000 for August alone, it's easy to see why. But how can it still be selling in that large of quantities when it's as old as it is? Well, there's several reasons for that, but it's important to note that a major factor is Microsoft hasn't provided a replacement.
And why should they? With sales numbers like this, they're finally making back the money they lost at the beginning of production. The Kinect was a key point in helping sell the console as it gave a sales boost and expanded the range of games that could be offered to consumers. Importantly, the Kinect allowed family games to be created and sold.
Microsoft has also turned the Xbox platform into a living room entertainment center, which has expanded its uses beyond just a gaming platform, similar to how the PS3 added a Blu-ray drive. It's widely believed the next Xbox will be announced sometime next year, though Microsoft has been silent on the topic.