I've heard rumors that the last edition was the last manual.
Porsche is not making a GT2 at all. The last GT2 was for the 2009 model year, then the skunkwerks GT2RS in 2011. They have said earlier this year that there are no plans to ressurect the GT2 moniker, but with appealing market demand, don't be surprised to see one at some point. Having a manual transmission, however, is more of a stretch, as nearly everything track-oriented is PDK now.
Porsche originally said no new GT2, by about 4 months ago AP said they probably will. Certainly will not be a manual.