Well, I'll do a little speculating, aka guessing, on this topic. The smaller the department, the greater the need for interoperability with their neighbors. As long as the big boys in a given area are still conventional rather than trunked, their smaller counterparts will be also.
Example: Several years ago, our former emergency manager was trying to talk the city into upgrading to a trunking system. He got as far as checking the available allocations for our area when the FCC advised that we would have to allow the smaller agencies in the area to use the system if they could purchase the necessary radios. They would NOT have to contribute to the cost of constructing the system or maintaining it. Well, that went over like a ton of bricks. So, no trunking system for the Stillwater/Payne County area.
As for the audio, I expect that conventional analog will be the norm in most areas, due to the cost factor. Interoperability issues may impact that, not to mention government requirements.
But Rob is right, there is no definate answer. Time will tell.
Mark S.