I doubt they're going to be very SURPRISED that they get beaten badly in September, so I don't think it will drive them to a 2014 price cut.
There's also the question of perception, more specifically on the desirability of the product. Microsoft's been very careful lately not to touch on exact numbers, and not to set itself up to be directly compared to the PS4 in terms of sales figures. But sales figures aren't the only things that can demonstrate a product's momentum... often, the way pricing, bundles and deals are handled are as much an indication. Look at Germany; the Xbox One is being absolutely wrecked in that market, and so one of the most startlingly generous bundles arose from that region.
Even in the U.S., where the console is getting outsold by its competitor, but not nearly as badly as in Europe, there's a different mindset to bundles; Xbox One bundles-with-a-game give the game away, literally, for free. The Destiny bundle, meanwhile, has only a small discount on the game. Even without knowing about the sales lead implicitly, it isn't hard to figure which company is having to work harder, and dig deeper, to try and make itself interesting to the wider consumer market.
A price drop, only a few months after the cheaper Kinectless model, and during the same period you are seeing bundles that give a game away for FREE, would just make the company look a bit desperate. Not because they're lowering the price, but because they're lowering it so soon after all these other sales-booting initiatives were put into action, not even feeling comfortable or confident enough to wait until after the holidays to see how their new title releases and bundles pan out. It's an image of vulnerability, one Microsoft is likely going out of its way to avoid projecting.
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