Valve is actually occupied with supporting and maintaining Vulkan API SDK's and the OpenGPU initiative with AMD.
I was at Valve dev conference some years back and they talked about porting most games to Linux and the OpenGL support. Most of the conference is on YouTube I believe.
They are busy with making the most "complete" Steam platform, by this I mean that they're porting/adapting code all over the place.
I would love a L4D3 and HL3, but then again, so would most people and Valve's still silent about any of that. So I'm guessing I'm right about the code and dev part.







