In Europe, see [link=http://www.manthey-racing.de/nextshopcms/show.asp?lang=de&e1=221&ssid=1&mdocid=329&newsid=477]http://www.manthey-racing.de/nextshopcms/show.asp?lang=de&e1=221&ssid=1&mdocid=329&newsid=477[/link] It refers to the Sports Cup Europe which is here [link=http://www.porsche.com/porschesportscup-germany/]http://www.porsche.com/porschesportscup-germany/[/link] In the USA, there are several series being planned although they seem to be either unique to the Cayman GT4, or sub-classes of existing series.
There is some life left in the old boy with the RSR of Patrick Pilet winning GT Le Mans series in the USA including an outright win with Nick Tandy in the wet at Road Atlanta against LMP2 type cars. The RSR also won WEC's LMGTE Pro Championship and Pilet was Champion in this as well.
I think the GT4 Clubsport at 1300kg with 380hp is going to struggle in FIA/Euro GT4 classes (Ginetta G50 has 340hp and weighs 1010kg) but it is a BoP series which in 2015 was won in a Camaro.....