Right now the PS4 has a lot going for it. Positive buzz and cheap price point. However it lacks a wow factor. So while i see it outselling its competitors i don't see it growing the market. In fact i see the next gen overall selling less than this gen if things stay as they are now.
Don't also forget that the Xbone has options. If sales are seriously bad then MS will act and they will act fast. They've proven this with Kinect, pricing, bundles, and removing the DRM stuff. They can very easily remove kinect from the bundle...and sell the system without it at ~$100 cheaper.
Although that will be a last resort. Their main priority right now needs to be showing off the added value of the extra cost. They really need to start refocusing on Kinect. To be more specific they need to focus on Kinect Games.