In fact, I'm a big fan of how Microsoft does versioning, supporting previous versions, but releasing major versions with backwards incompatible changes. You see this in DirectX, and IMO, that's why we're talking about DirectX and Vulkan, rather than AZDO OpenGL these days. It really gives you an opportunity to clean up the cruft.
Metal uses Objective-C/Swift, with shaders in C++14. The Objective-C runtime can be used as FFI.
DirectX, uses COM with HLSL (a C++ subset). Likewise any COM or .NET (via RCW) aware language can talk to it.
One of the reasons OpenCL lost to CUDA was being stuck with C, while CUDA offered C, C++, Fortran and any additional language that could target PTX.
Which was what eventually made them come up with SPIR and later SPIR-V.
NVN and LibCGNM are also based on C++ and C++ inspired shader languages.
All modern OO, with nice SDKs that handle font, texture, materials, maths, GPGPU debugging.
They just decided to release 1.0 without generics, instead of waiting for it to be 100% ready.
As Don clearly describes on his blog.