I think the only "Obvious conclusion" after four games this season is that there is no obvious conclusion.
I'd call the NFL since 2000, "The Belichick Era." By that I mean that any team that is well coached, has a good+ starting QB, escapes devastating injuries and plays a tough 60 minutes of football for 16 weeks can be in it at the end.
In the NFC, the Pack is playing lights out, but yesterday, the Giants reminded us, maddeningly, that they have a QB who plays little better than average most of the time and then can seize a lucky break or an opportunity and play lights out when he has to (two TD's in 58 seconds). And, as much as we like to dis him, Rex Grossman has taken a team to the SB and is now playing for an HC who's taken home the big bling twice. The Lions could prove to be the real deal.
In the AFC, I don't see any team dominating at this point. The Pats are among a cadre of very good teams with important weaknesses; the Ravens look like they might be ready to put it all together in a year when the Steelers are faltering, but, I wouldn't rule out any AFC team with two or more wins from being in the mix until the end.
Bottom line. Fasten your seat belts.