Originally posted by Don Cardi:
Looking at the dialogue in that scene and listening to it, Michael is not neccesarily making a reference to killing a President. Yes, Tom makes the analogy that killing Roth while in custody would be like killing a President, but Mike is not necessarily making a reference in his reply to the killing of a past President! Maybe by saying to Tom " You Suprise me, if anything in this life is certain -- if history has taught us anything -- it's that you can kill anybody, Mike could have really been saying, as an inside message to Tom, " You suprise me Tom, if the history of The Corleone family has taught us anything, it's that you can kill anybody. You suprise me, we killed a Police Captain, and the heads of the five families when everyone else thought that we were weak and that it was virtually impossible for us to do so!"
Don Cardi 
I think that's a valid viewpoint, DC--especially the part about McCluskey. At that time, Tom said it would be impossible to kill a police captain--"outcasts"--and Michael came right back at him. Perhaps the "you can kill anyone" remark was a reminder to Tom.
When I said earlier that FFC was appealing to our
consciousness of the JFK assassination, I meant that he was cashing in on what we, the viewers, already knew--not what the Corleone family might have been planning down the road.
