Snake Eyes, if that was the case GF4 would be a repetition of GF1 (the innocent son become like his terrifying father etc.)

like that they can go on making a Godfather movie on and on and on, GF5, GF6, in 2078 a GF31 will be there.

and quite frankly, I think they should end it sooner or later...

Now I've become a big fan the last couple of years, but never really went to a brand new GF film, so I dig the idea of a GF4 if well done (but I think it will destroy the saga anyway). After that, they should REALLY end it.