Good topic!

I don't think The Godfather would be as good today because of a few reasons:

A) We already have The Sopranos to represent today's mob family

B) Time difference brings on a classical feel to this movie

C) RICO

D) Ever since the Pizza Connection, the mafia has been too caught up in narcotics. Vito's philosophy on drugs would have never held up in today's cosa nostra.

E) Too many betrayals. Sure, the Corleone Family had their share of traitors (Carlo, Tessio) but I believe that in today's family, if they had a problem with loyalty, it wouldn't be a few individuals. I'm thinking people would come together against them, weakening them even more. Imagine if Tessio, Paulie, and Carlo decided to start their own family, league, or coalition and started recruiting thugs off the street. Though it probably wouldn't hold up against some of the stronger families, the Corleone's would have been made weak due to the information known by Tessio, and maybe even Paulie. It's just how strategies, and values have changed.

F) Making a GF based on today is like making a new Romeo and Juliet based on today. We know that wasn't a good idea!

Anyway, that's my opinion.