If Lucas wanted to go the route of a fake death, he certainly has built-up that option with the whole decoy thing.
Anakin going crazy and killing off Jedi and Seperatists would likely clue her in to the fact that he's lost his way........
For the safety of the children, she would have no option but to live under an assumed name (if she lives). I kind of liked the idea of Padme watching over Leia from a distance like Obi did for Luke. Then she succumbs to injuries of some sort a few years later. That way Leia has her memories......
But that won't happen because Lucas will want to wrap up the story in this film, which is understandable.