Maybe before The Sopranos a modern-era Godfather film could have worked. But after that show has ingrained itself into society, I think a Godfather film about those same themes (rats, depression, double crosses, technology, culteral clashes) would feel like a rip-off. And when taking into consideration all the GF references in The Sopranos, it would be ironic.

Kind of like how James Bond movies just never seemed as cool as they were after Austin Powers came out.