A problem is probably that there is that there are just a ton more Nvidia cards out there, and CUDA is hard to keep up with, so nobody is doing to invest in an alternative more open language.
A possible solution (that doesn’t involve being better than Nvidia at the things they are good at, which seems to be impossible) is to create frameworks that spit out CUDA or, whatever, OpenCL. Nobody actually wants to use the languages, right? Everybody loves CuBLAS and CuDNN, not CUDA, make GPUOpenBLAS. Maybe they could get Intel to come along with them.
That's literally what they're doing. HIP supports Nvidia as a backend, and AMD are making replacements like MIOpen, which is intended as a quick-port replacement for cuDNN.
That is a very good question that apparently AMD has no good answer for. I have lost track of the amount of half baked implementations for GPGPU that AMD has attempted and then left to rot. Even if they told me they had the answer now, and they are going to put all their focus on that, I would not trust them to deliver on it. Their best bet is to create implementations for popular libraries like torch that actually stand a chance to work as a drop in replacement.
That said, what _is_ AMD's platform? OpenCL? Vulkan compute? If they don't have an alternative, then the strategy doesn't make sense.