The RS versions will always have PDK.
I have confirmation for a 991.2 GT3, a 991.2 GT2 RS but no 991.2 GT3 RS yet (however everyone is talking about it, rumor-wise, so I assume it is coming).
Since Porsche may present the 992 in 2018 already (autumn), there has been lately a strong rumor about that, it is pretty clear that all special edition and GT models of the 991 type will be available latest until 2018.
The reason for the hurry could be the fact that VW Group needs Porsche's new sportscar platform in place as soon as possible for cost and synergy reasons.
So far, the 992 was rumored for a 2019 release.
RC (Germany) - Rennteam Editor Porsche 991 Carrera 4 GTS Cabriolet (2015), Porsche Cayenne S Diesel (2017), Audi R8 V10 Plus (2016), Mini JCW (2015)