According to my source chances for manual 991 GT3 and 991 Turbo are slim or if you read between the lines  almost non existing.

At the same time my source ask me why is it so important to have manual option for those models. He told me that technical limits of previous 997.2 were the key element in preventing Porsche to use PDK for GT models.

He also wrote to me that PDK is a must for new 991 models and specially for forthcoming GT3 and Turbo. Porsche invested a lot in special version of new DFI engine that will be used in 991 GT3.

Personally, I am looking forward to see PDK only 991 GT3 and 991 Turbo.