I think you would be kidding yourself if you did not accept the fact that eventually everything will go digital over time. Now whether it will be encrypted or not, who knows. I tend to lean on the side that all emergency service communications will be encrypted. Just a hunch and nothing more.
The SERS radio system already has some digital stuff. And all of the ERT teams (aka SWAT) are encrypted.
With all of that said, the SERS radio system is still relativity new. It did not go fully active till Jan 07 and they still are going to have to restructure for the reband on the way. Then toss in the economic times and well........ I do not foresee any big digital move for a long time to come.