So here's the skinny. Right now the Packers are 12-3 with a conference record of 9-2, the Saints are 11-4 with a conference record of 9-2, and Seattle is 11-4 with a conference record of 8-3. Seattle has the common opponent tiebreak against both NO and GB should it apply.
If the Packers win or tie, they get the #1 seed no matter what by sheer record.
If the Packers lose and the Saints and Seattle win, then the Saints get the #1 seed by way of conference record, and Seattle gets the #2 seed by common opponent tiebreak.
If the Packers lose and the Saints lose, but Seattle wins, then Seattle gets the number one seed by way of common opponent tiebreak, the Packers would get the #2 seed and New Orleans would get the #3 seed.
If all three lose, then the Packers keep the #1 seed (and the Saints keep the #2 seed).
If the Packers lose, and Seattle wins, and New Orleans ties, then Seattle gets the #1 seed (by common opponents with Green Bay).
Also as I said elsewhere if New Orleans loses or ties, and Seattle wins, then Seattle will have no worse than the #2 seed.