As of now, it has to be plugged in to the console. Granted, Microsoft could change that while still including the Kinect with every xbone. That would be the best of both worlds. Everyone still has it so the devs could make use of it and those who are so inclined could still use it. Those who don't want to use it could leave it in the box.
Point being, it's a camera in the living room/bedroom that could be hacked or collect data.
Edit: the old "cover it up/face it against the wall" argument is a bit premature. For all we know, the console may bring up an "error. Configure Kinect before proceeding" message. It hasn't been confirmed but it also hasn't been denied so it should still be treated as a possibility at this time.