I kind of wonder if they might not do what they've done with the Lumia 950, which is give an option to switch to the full Windows interface, if you desire to do so, but have the default interface a customized experience for the device. So basically, boot your console to a console interface that makes it very fast and easy to navigate for all the basic gaming, social and media features. Plug in a keyboard and mouse, select a menu option and you're in the full Windows UI with the Xbox App. Yah, there are memory and performance considerations for that, but it may be the route they choose to go.