Ok. But in order of appearance, it's really 1) Vader 2) Sidious 3) Maul 4 ) Dooku. They haven't really been making the antagonists progressively closer to the heroes like you insinuated. Anyway, how can you make the villain in the ST someone the main characters are all emotionally attached to? Leia turns to the dark side? Either way the new villain will be new to the audience. Besides, Plageuis could play the Master while his apprentice is someone that 'hits closer to home'. You can get the best of both worlds.