Packers and Bears are both tough games (with the Bears much better lately). The Vikes should beat the Chargers handily, but the Chargers are one of those teams capable of pulling a pretty big upset - at least talent-wise, not sure about their heart. And this game is on the road for the Vikes.
With the Packers game being game 15 instead of 16, they will be motivated to win since home field/bye week will still be undecided.
The Bears will likely be out of the playoffs before the final game. But it is a division game and the teams don't like each other. Hopefully the Bears will be motivated for the last game of the season.
