The entire point of a controller or mouse is to simplify movement. It's way easier to move an analog stick or mouse 5 millimeters than to wave your arms around. Full motion capture interfaces look cool, like the ones in Minority Report, but they suck to use for more than a brief gimmick. I don't see it succeeding unless it includes a controller, and the motion-capture is relegated to the mini-game gimmick status of Wii's waggle.