I don't know why you guys stuck to this idea of flashbacks...

maybe it would be good, specially with De Niro playing Vito, but there are many other possibilities. (I hope no one to be made and I think no one actually will)

I believe Pacino and FFC would not agree to make GF4. Pacino is just a guess, but we know FFC seems regretful about GF3 (I saw him on actor's studio and he didn't look happy about having made part III)

Also, I think (and I hope all of you agree with me, please!!!) a godfather movie without Al Pacino would be ABSOLUTELY ridiculous