> HLSL evolution roadmap
...that's just because of the traditional-game-dev Stockholm syndrome towards C++ (but not too much C++ please!).
> Khronos future for Vulkan
As far as I'm aware Khronos is not planning to move the Vulkan API to C++ - and the 'modern C++' sample code which adds a C++ RAII wrapper on top of the Vulkan C API does more harm than good (especially since lifetime management for Vulkan object is a bit more involved than just adding a class wrapper with a destructor).
See the talks around Vulkan ecosystem, and GPU shading languages from February.
There is more than one sample using C++, now they make use of C++20, including modules if desired.