The Falcons made things simpler. The Falcons already have nine victories. They face Tampa Bay in Week 17. It is likely, then, for Atlanta to finish this season with 10 victories. New Orleans already has 10 and will likely have more. It is likely, then, for the NFC South to produce two playoff teams this season. The Seahawks and Cardinals can win no more than nine games apiece.
Which teams to root against. Seattle and Arizona fans should root for Detroit (8-5) to lose. They should root for the second-place teams from the NFC East to struggle. The Seahawks can reach the playoffs even if the Lions finish 9-7. The Cardinals can as well, but when I played around with scenarios, Arizona needed the Falcons to miss the playoffs at 9-7.
One edge for Seattle. In at least one scenario, the Cardinals would lose a three-way tiebreaker with Dallas and Detroit if all three finished 9-7. Seattle would win that tiebreaker if the Seahawks finished 9-7 with a victory at Arizona in Week 17.
Lots of scenarios to consider. The Playoff Machine makes it easy to see which teams would advance to the playoffs based on specific outcomes. It does not tell us all the ways specific teams could reach the playoffs. If you have that information or know where it can be found, please share. I'd like to see all the scenarios.