it's already underway. the MGEG software was patched a couple of months ago, since they are already running GTR/GGM hardware, it's only a matter of patching the sites. All of that went down when the new CAD was rolled out after the 1st of the year.
Not sure about new subscriber units. But I have heard by the end of the year per the contract.
Encryption use won't change from what it is currently (which is only on specialized talkgroups like SWAT, MCS, etc).