Now I could just be setting myself up for major disappointment and probably am, but since Force Unleashed takes place between the trilogies maybe that's how marketing will tie in the boxset. Of course, it will probably be no different from the way Shadows of the Empire handled things, taking its time in the sun until something else came along a few months later (the '97 SE). 2008 will probably be similar, first Force Unleashed in the Spring and then The Clone Wars in the Fall returning Star Wars to the small screen after a long absence just as the SE returned it to the big screen after a long absence.
But I dunno, this is just me theorizing that they wouldn't release a new dvd set without a new videogame and just figured they couldn't wedge in the grand multimedia event of The Force Unleashed when there's a 30th anniversary toys/ comics/ books sale already going on. We'll just have to wait and see what really happens.