Bam,
It is hard to imagine anyone but Gandolfini in the role but hey, never say never. Anything is possible I guess.
TIS
I really doubt they would replace the role of Tony Soprano unless they want to pull a Godfather Part II and have somebody play as the younger Tony.
The only way they could do that imo is if the story centers around Johnny.
I always liked those flashback seens with Johnny Soprano, a young Junior and Olivia. I liked when Olivia said she wanted to stick the fork in young Tony's eye.
