SYCL also doesn't meet the listed requirement of 'Intel and AMD teaming up'. Intel seems to be the only hardware vendor to actually care about SYCL, and AMD is instead backing HIP which is 'standardized' but boils down to 'just take cuda and run :s/cu/hip/g'.

If AMD were to work on SYCL tooling and, say, build a 'syclcc' next to 'hipcc' that ingested SYCL to run it on ROCm, I feel like interest in SYCL could potentially grow, since Intel is supporting it properly already and it would be actually a cross-vendor standard.

Codeplay (which is part of Intel) does provide 'plugins' to run oneAPI (SYCL) on NVIDIA and AMD hardware, which is great but is still being made, indirectly, by Intel, who in the end want to sell Intel hardware.