Barring any key injuries, I think the floor for the Panthers is 7-9. We'd probably see something similar to 2012 in that they'd get the short end of the stick in some close games and generally not get the luck they did in 2013. I predict the NFC South to be the second best division in the NFL behind the NFC West and that could cost the Panthers a couple wins on sheer improvement of the divisional opponents alone. Defenses might have an easy time getting to Cam Newton with an inexperienced offensive line and all new receiving corp, but the defense is too good to fall below this. As long as the defense is close to as good as 2013 and Cam Newton is under center, at the very worst they will finish around .500.
Ceiling is 12-4. I don't think the Panthers can improve on their record from 2013 given some key areas of roster deficiency but they could match it if everything bounces their way again. This would require the receivers overachieving and the offensive line gelling quickly. They've got some young players slated to start on the offensive line and that is a major question mark. The Panthers play ball-control offense and you need a good offensive line to do that. O-Line needs to step up quick and Riverboat Ron needs to show that his magic from 2013 wasn't a fluke.
tl;dr - Floor = 7-9. Ceiling = 12-4. What do you think?