This is an intriguing concept. I like it. It would definitely reduce the possibility of 8-8 and under division champs.The problem is not the four-team divisions, the problem is that these teams only play 6 of 16 games in their division. It would make more sense, I think, for each team to play three games against each team in the division, two at home and one away, or one at home and two away against each other team, and it alternates each season. This way, Pittsburgh would play at Baltimore twice in one year and once the next year, and vice versa. In this system, each team would play nine games inside the division and seven outside the division. One way to schedule the other games is that you would play an entire division in the other conference as we currently have, but you would play three the three other teams in your conference who finished the same as you did last year. For example, if the Broncos win the AFC West, the next season they would play all three AFC division winners, and second place teams would play the other second place teams. We currently have that system in place.
Increasing the number of divisional games would greatly reduce the probability of a sub-.500 division winner.
In the meantime, assuming no tweaking of the regular season takes place, I say leave the playoff formula alone except that if you're a division champion, you also have to be above .500 to get into the playoffs. Otherwise, a third WC gets in, provided they are above .500. If there aren't any >.500 teams available, then the original lame division champ gets in. (same concept that JuggernautJ and rihickok mentioned but fleshed out a bit) I first thought of this back in 2010 when the 7-9 Seahawks got in.
So that year, instead of the NFC seeding looking like this...
1. Falcons
2. Bears
3. Eagles
4. Seahawks
5. Saints
6. Packers
...it would look like this...
1. Falcons
2. Bears
3. Eagles
4. Saints
5. Packers
6. Giants