I believe that eventually in the future it might become a "war" between the police having some form of device on them that prevents a phone from even being able to be turned on within a large radius, let alone being able to record audio/video, and those trying to record such acts. If anything, it might also turn into a thing of people turning to creative and innovative ways to get around that technology in that potential future and the police responding with updates that make whatever we use to counter absolutely meaningless.

It might turn into a thing - if it happens/becomes reality - that the vast majority people get used to it, similar to how in Japan, phones made specially for their market are required to have a sound go off when the camera is used. That's a future we don't want or need.