But by telling everyone that they are bluffing, the threat letters will lose their power to affect behavior.
I doubt that.
People have been getting these DMCA letters for years, and users have been pointing out how on most carriers they aren't backed up by any solid action for just as long. That hasn't stopped people from freaking out every time they get one, and I bet there's oceans of moms and dads out there who'll get these letters and put a stop to junior's P2P use right quick, regardless of some tech forum's statement that this is, in essence, a bluff.
Sooner or later Verizon will have to actually stop bluffing and start tossing customers.
Not unless there's a law, and there isn't one yet.