I’m wondering id KCD will use the new Nvidia OGL extensions and OGL 4.4 and the AMD equivalents that will be a part of Cryengine in the future.
I am assuming this will be the case since it is comming to Linux and will be using the latest Cryengine.
I think that the game would not require it to run. Playstation 4 apparently supports OGL 4.0 and even on gaming PC’s 
http://store.steampowered.com/hwsurvey
Linux drivers for Intel cards also support OGL up to 4.0. ATI and NVIDIA support 4.4, but these cards are not used on Linux as much.
Regarding extensions, I do not know much about that. But some of the Nvidia extensions are de facto standard, widely supported across all hardware vendors, so it might be possible that the game / CryEngine will make heavy use of it.
It all depends on how much are the developers going to invest into “progressive enhancement” I think.
iam wondering to. Iam glad that we now see changes in the low Level API sector. Its quite exciting and Long overdue.