Some people really need to understand the difference between intimidating and being a jerk. How about instead of causing other teams' fans not to come because of bad behavior, we cause them not to come by buying more tickets ourselves? 
Or instead of causing fans to fear coming here because we're jerks, they don't come out of respect for how loud the fanbase is and how much we razz their team on the ice instead of razzing them as individuals in the stands?
It's easier said than done. When going to a Devils game is ALWAYS the cheaper option for a Rangers fan or Flyers fan, they're going to go on StubHub and buy tickets, simple as that. You're not taking into account the amount of antagonism and drunken hostility that comes with having a few Flyers fans in your row. What do you do when a Flyers fan chick tells a mom "I hope you die of breast cancer!" (actually heard this during the playoffs last year) after the mom told her to stop cursing? Prudential Center security sure as sh!t won't kick her out, they never do.
Fact is, we don't want those types of people coming to our arena anymore. When they get loud and the Devils end up winning, we have full license to humiliate and offend them. If you don't think that has been an active cause of why we're seeing less and less Flyers/Rangers fans in our arena, you need to get real! The loudmouth Rangers or Flyers fan that thought he was going to have full reign at The Rock to have a nice evening, get drunk, and be irresponsible, and NOT get kicked out by security, they need the rude awakening and Devils fans are growing some balls. The unfortunate side effect is that it pours over into other games, but I like rivalry games at The Rock WAY more now than I did 3-4 years ago so it's good enough for me.
If you're a Devils fan you need to know what you're getting into by bringing your kids to one of the uppers/200s sections during a Devils-Flyers game. There's a lot of things you can't bring your kids to: R-rated movies, nightclubs. I hate to sound harsh but the responsible adult should know better before getting tickets to the upper sections in these games specifically.
Let me just add that, to all of you saying that some of the idiots should COOL IT during non-rival or non-division games, I completely agree.