Darth Lucas said:

I have a theory. Everybody is talking about the hooded figure speculating he may be an ancient warrior of some kind. What if this character turns out to be Darth Plagueis? He actually DID manage to save himself from death and has been in some form of hibernation for years and years. The shot from the trailer is him waking up and igniting his lightsaber ready to kick some ass. The force awakens. As in the ultimate user of the force awakens. Huh? Huh???

I know it's dumb but I love speculation like this ^-^

I would really hate that. Palpatine thought he killed him. And I've always thought he was strong enough with the force/wise enough/aware enough to know whether or not he killed someone. And he could feel the "disturbance" in the force Luke showed... and he couldn't since a sorth lord? I would really hate to have Palpatine turned into a little bitch like that :P