If Sony does have this bundle in the works I would expect them to announce it October...a few weeks before the launch of Kinect. They might as well sell as many units as possible at the $399 price tag then offer a less expenisve option to maintain interest in Move and try to persuade potential Kinect buyers to the PS3. It will also make PS3 bundle a little more attractive for the holidays.
Pretty much the same move Microsoft did with the 360S and releasing the arcade version a month later.