Of course not! There are plenty of actors who would have done a well enough job to get by, but Pacino really brought out the complex character of Michael Corleone. Just try and imagine, Charlie Sheen (who was almost forced on FFC to play the role by Paramount) playing Micheal Corleone. I mean, Sheen is a great actor but I can't picture anybody but Pacino for this role.
NO! Are you out of your fucking mind?! Pacino perfectly played his transition from "Joe College" to Don Corleone. It was very subtle in a way, yet very obvious, and I dont think anyone else could have pulled it off the way Pacino did.
I say no because it is extremely hard to imagine Michael played by another actor.
If someone else had played Michael, for example Robert De Niro, I bet we'd all be saying that no one would have been able to have done a better job of playing him. Anyone get where I'm going with this?
One point about Kay is that Michael said in the 1st film that the business would be legitemate in 5 years. So Kay did know the nature of the business, but on that understanding.