The Steelers are a fluke, like the Buccaneers' one Super Bowl. Roethlisberger is a second tier quarterback, they've got no running game and if they get Mike Tomlin as coach, they're going to have to blow up the team defensive personnel. The players they have won't fit his defense. They're almost starting over again.
I see the Chargers as legit contenders for years to come and Rivers really need to pop his playoff cherry; the vast majority green playoff QBs don't fare well their first time playing in January. They're deadly, though, because L.T. is arguably the best back in the game, Rivers is looking like a Pro Bowl-caliber QB and Antonio Gates is one of the best TEs in the game. They've got a very balanced set of offensive weapons.
I just don't see the Bengals doing it. Carson Palmer and Chad Johnson are good, but they're just a poor man's Peyton and Harrison. And the team is an undisciplined disaster.
Contenders likes the Ravens and Chiefs are in decline. I'll be keeping my eyes on the Jets, though.
As for the NFC - it's a mess. The Saints have one of the most balanced teams in the NFL, but are a few pieces short on defense. The Bears need a consistent offense. The Seahawks just lack the talent and I think both Hasselbeck and Alexander have peaked. Next year will be a transition year for the conference, but if I was a betting man - I'd see the Saints representing the NFC in next year's Super Bowl.