Earlier quoted context omitted.
What does CUDA support that Metal 2 cannot do? Recently I've been implementing some 3D mesh algorithms in Metal 2, and it was quite easy to do.
Support for all the CUDA code that's already out there. Not that I've used Metal, but that's what seems to be the reason behind OpenCL's lack of adoption
So, my bold prediction: Apple is going to shred Nvidia to pieces within the next 10 years.