Leaving the politics aside...I'm not up to speed on all of the technical aspects of this. Will a Uniden 396T pick it up?
The 396T only supports P25 phase 1.
Once the system core is upgraded, and all subscriber units are replaced with phase 2 radios, then talkgroups that transmit in phase 2 will not be heard on your 396T.
You will have to upgrade to one of the (soon to be released) BCD-436 or BCD-536 Uniden scanners which support P25 phase 2, or if you can find one, a GRE PSR-800.
Note: the new North Fulton Unified Radio System (URS) that Sandy Springs, Johns Creek, Alpharetta, Roswell and possibly other CHATCOMM agencies like Dunwoody will be moving to this system, which will be a full P25 phase 2 as well.
However, most public safety talkgroups will use encryption from what I have heard.
The new Fulton county DTRS (not to be confused with the URS) is also a P25 phase 2, though for the first couple of years, most talkgroups will be phase 1 as they are not replacing all their subscriber radios when the new system is brought online.