it would of course depend on how far back he dissapeared, and who was still on the Jedi council from back then, it might explain why Yoda is so distrustful of Palpatine, perhaps Sifo Dias was a lot older than his clone and more resembled the Emperor as he appears in ROTJ?
I guess we won't know until next May, but I still think I'm on the right track,
As there hasn't been any major revelations in this new trilogy to match the magnitude of Vader being Luke as well as Leia's father , I'm beginning to think that Darth Sidious's Identity may turn out to be a big surpise to everyone, the sidious/palpatine connection might just be a little too obvious to be true.