While watching the flashback scene this weekend, I noticed something else. I've posted before that Michael sits on the right side of the table while everyone else is on the left side except Sonny who sits at the head. Thus, FFC illustrates Michael's estrangement (to an extent) from his family. However, I noticed how Sonny dismisses some of the family. He tells Connie to, essentially, shut up; he orders Fredo to get him a drink. He insinuates that Tom is a Jap-lover. Of course, he physically assaults Michael and demeans him.

So, coming at the end of the movie, it's a cogent summation of what we just viewed during the previous 6-7 hours during I and II. Sonny lives by the sword and dies by it; Tom's loyalty to Vito is almost slavish and earns Michael's enmity; Fredo is doomed; Connie is of no account; Michael will always pursue his own objectives.