I suspect that if the architecture of the 996p2 and 325p2 support DMR, the HP2 probably can. However, it's another thing entirely whether Uniden would offer such an upgrade. And as indicated, they have not to date, and have not indicated that they ever will.
Mark
536/436/WS1095/HP1/HP2/996T/996XT/996P2/396XT/325P2/PSR800/15X/others