I'm not sure what the FCC is going to do, but it would likely have to do with affecting future scanner design. There's not much they can do to current recievers. They might have a law, but it's not practical to enforce. Sort of like when they made it illegal to listen to the old analog cell phone calls.

I'm sure they could figure out ways to scramble things on the transmit side though, although it would be less than cost effective. Many larger departments are doing a lot of dispatching over computers even from car to car, so radio chatter is way down except for emergencies.

As far as codes, as everyone said, they can vary widely, but the feds are trying to convince departments, police and fire and any other emergency responder and even private companies that may have emergency responsders to go to a plain language system. The idea being that all responders will not revert to a code system that other responders can't understand during a wide area event or emergency.