As an aside: why won't everyone migrate to Vulkan compute shaders? I hate these "special" compute stacks >_< Clearly I'm not alone in thinking this: Tencent's ncnn uses Vulkan as the only GPU option, some Googler is working on clspv (OpenCL to Vulkan SPIR-V compiler)..
1. No libraries. cudnn, cublas, cufft, are all the fastest available (except maybe magma sometimes), plus no one writing an actual application wants to reinvent a fast gemm. Also cutlass, cub, thrust, ...
2. No c++. The "standard" seems to be glsl, and a "prototype" opencl c -> spir-v compiler doesn't give me much confidence in that approach.
3. No one wants to use vulkan apis directly, and there are approximately 5 billion different "vulkan compute" wrapper utility libraries. i.e. No consistent platform.
Vulkan compute and OpenCL are not entirely compatible (both are backed by SPIR-V (but different flavors of it.)) Khronos has chosen to maintain OpenCL (and OpenCL-next) separate from Vulkan.