Though i know you can't really go off of The Godfather Returns, they do mention 7 families on the commission. Taking into account that the Corleones moved to Las Vegas, that would leave one of the families, more than likely Stracci's to fill the void as the new fifth family. so you would have Las Vegas, the five New York families, and Chicago.

"Death is the answer to all problems. No man, no problem."

"I'd rather be hated for who i am, than loved for who i am not"