I am not denying that C++ is very relevant for CUDA (since version 3.0), it is also why I never bothered to touch OpenCL.
And when Khronos woke up for that fact, alongside SPIR, it was already too late for anyone to care.
Regarding the trees, I guess my point is that regardless of tiny they are, the developers behind those stacks rather bet on CUDA and eventually collaborate with NVidia than going after to the alternatives.
So the alternatives to CUDA aren't even able to significally atract those devs to their platforms, given the tooling around CUDA to support their efforts.
And when Khronos woke up for that fact, alongside SPIR, it was already too late for anyone to care.
Regarding the trees, I guess my point is that regardless of tiny they are, the developers behind those stacks rather bet on CUDA and eventually collaborate with NVidia than going after to the alternatives.
So the alternatives to CUDA aren't even able to significally atract those devs to their platforms, given the tooling around CUDA to support their efforts.