I kind of like the concept of Anakin having a dream of Vader killing Padme. In some way he sees the futur, but don't understand it (could mirror Yoda's teaching in ESB, "difficult to see the future is"). It could even make that horrible "Nooooooo!" line works (not that I want to keep it!) because he realises (and the audience too) that not only the dream happened but he was that masked man. He knew it but did not understand. There is no way to escape to the dark side: even if you think you're doing the right thing it will turn bad. I think it is already more or less Lucas's vision of the story, but if we want to follow that same idea (but maybe we don't want!) it would be more effective with this dream part. But it's tricky...