Well, I doubt that the producers anticipate stretching this series out over another seven years to accomodate historical accuracy.
I wouldn't be suprised if I were you. And who says Rothstein needs to die in the first place?
He doesn't have to die, i just thought the "Their Time Has Passed" reference to him and Nucky might have meant they were going to move on Rothstein. But as it was pointed out to me he really didn't die until 1928 so i guess he should be around for the forseeable future if they stick close to the real timeline with that particular character.
