The problem with this theory is that there are others who have been referred to as Godfathers:

Sheldon Adelson is the Godfather of the Repubs.

Soros is the godfather of the democratic party.

Bill Clinton has been referred to as the godfather.

Charles Koch has references too.

James Comey makes the list as well.

George bush has been referred to as the godfather for his role as head of the CIA. Did his son Jeb inherit the role?

George Shultz has been referred to as this as well.

Henry Kissinger oversaw a criminal cabal & Godfather reference has been made. HRC is said to have been his accolyte. Did she inherit his role>

All of these have multiple references as well. I imagine there are others like the pope? Also to think of the Godfather as just Jeff Sessions is quite narrow in scope. This is an international counter coup. Sessions is pretty small on that stage. I am sure European and Asian Politics have Godfather references as well. In addition, All these figures were opposed to good. Sessions, we hope is a white hat. No one in the Godfather series role was a white hat in the movie.

In keeping with the movie of mobster fame, perhaps the Godfather is the taking out of all the other Godfathers! In the movie there was the 5 families that worked in concert with each other to control the world with the corrupt pope. Between the families there could be murderous breakdowns as each family jockeyed for greater control. In the end the new young Godfather wipes out the pope and the heads of all the other families taking revenge and solidifying their dominance over all the territories to secure their own safety. The hero of the story safely leaves the business since no other Doms remain to take him out.

Q's mission is larger than Sessions role. Q usually is more complex than this theory takes into account.