I'm from Codeplay and I am not sure about what you mean from your comment about Level0. Intel have developed a back-end for DPC++ that supports Intel processors through OpenCL and SPIR-V. Codeplay has implemented a back-end that supports Nvidia processors by using PTX instructions in the same way that native CUDA code does. PTX is the equivalent to SPIR for Nvidia processors. Maybe I am misunderstanding so apologies if that is the case.
Intel are supporting SYCL in a big way. They are implementing SYCL in the open source LLVM project, the project is called DPC++. Argonne National Labs are also using SYCL to program the exascale supercomputer (Aurora) they are building. Whilst it's not the best solution for everyone there is certainly industry support for it.
I don't necessarily have an opinion either way in this discussion but wanted to point out that Intel's latest MKL library does seem to be done as an open source project https://github.com/oneapi-src/oneMKL