In the case of these abstraction layers, then it would be the responsibility of the abstraction maintainers (or AMD) to port them. Obviously, someone who does not even use CUDA would not use HIP either.
To be honest, I have a hard time believing that a truly zero-effort solution exists. Especially one that gets high performance. Once you start talking about the full stack, there are too many potholes and sharp edges to believe that it will really work. So I am highly skeptical of original article. Not that I wouldn't want to be proved wrong. But what they're claiming to do is a big lift, even taking HIP as a starting point.
The easiest, fastest (for end users), highest-performance solution for ML will come when the ecosystem integrates it natively. HIP would be a way to get there faster, but it will take nonzero effort from CUDA-proficient engineers to get there.