Will be interesting to see how the 49ers play it over the final three games. Plenty of players banged up who could do with a rest. Can't see the Eagles slipping up too badly, but it's close for second seed with the Vikings. They should beat the Colts tomorrow to clinch the division and move a win ahead of the 49ers. They then have the Giants at home, Packers away and Bears away to finish, all games that I expect them to win, so even if the 49ers were to win out the rest of the season then they still end up as 3rd seed. The best the NFC South can do is the Buccs who can potentially get to 10 wins, so the 49ers almost certainly have 3rd spot tied up. I would certainly expect a lot of players to be used very sparingly for the last 3 games, Josh Johnson might even get to start one or two.
Edit: afaik the 49ers can't fall below 3rd as they hold the tie breaker over the Buccs.