NYC isn't going to want guys running around with rifles in the Manhatten subways and sewers.
I suspect they're going to have a hard time killing their rats. Between all the restrictions NYC has on killing rats, to people's squeamishness about the issue, the inevitable media feedback loop that will develop around any techniques. . . not much will happen.
Unless something really surprising happens, I forsee someone stepping forward with some sort of chemical sterilization "catch and release" gimmick or something else, equally ineffective and giving positive PR to the appropriate target demographic.
