Maybe there'll be more than one person there? Like, them all there, joined by your PC if you choose the DS route? That'd be interesting... JOINING the final enemy(s)
Or maybe we won't just see sith there... Maybe we'll see jedi, standing in a nice heroic pose. Or maybe to start with you'll just have clouds, and as the game progresses you can see what your opponent looks like...
Just spewing ideas here, but it makes you think...