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I have long thought that a good plot for a Hollywood-ish movie would be that Reagan was actually killed in the shooting, and that the CIA or whatever had a double ready to step into his shoes and do their bidding. No one would be easier to imitate than an actor: Reagan normally had his face plastered with a ton of make-up anyway, and his remarkably wooden and stereotyped behavior and speech would also be easy to fake. As long as his wife and maybe a doctor or two were in on the plot, I don't see why it couldn't succeed.
