What's not open about HSA? If Intel and Nvidia haven't joined it (yet) doesn't mean it's not open. Nvidia treats OpenCL as 2nd class citizen compared to CUDA anyway, and I don't think Intel is that interested in OpenCL anymore, now that they have Phi. So if neither party is too interested in OpenCL, then I'd rather have HSA than the actual proprietary CUDA/Phi solutions.