A GF IV is okay for me, but a remake isn't. The best part about GF I and II were the actors, who were some of the best of the last 30 years (Brando, De Niro, Pacino, Caan, Duvall,...). Plus they played their top part in The GF, an accumulation of quality
Actors whoressemble them could play a younger version of the characters in flashbacks in GF IV, but they could never replace the originals.
And who should direct it? Scorsese, Sergio Leone (is he still alive), ... ??