I've been playing around a lot with the Playoff Machine on ESPN just to see what scenarios will work and it really isn't that bad of a proposition for the Lions.

1. (Most Important) the Lions HAVE to win at least 2 of the 4 games remaining to have any shot.
2. If they win 3/4 (loss to GB) than they are in. Only way this isn't true is if the Bears win out which is unlikely with GB in week 16. so potentially the Lions could have the playoffs locked up before even playing week 17.
   
3. if the Falcons win out or even 3/4 they lock up the #5 spot and get the NFC East winner. I say this because NO would have to pretty much lose out for DAL or NY to catch them for the #4 spot.
4. the Lions can catch and pass the Falcons for the #5 spot - and avoid a rematch with NO - if they win 3/4 and the Falcons go 2-2 which is possible if the lose in CAR and in NO.
   

there are some other scenarios out there, but really no matter how I flipped the games these scenarios all worked out.