The specification for SYCL 1.2.1, which is based on OpenCL 1.2, has been finalized and released on the Khronos website. The describe it as a major update over the previous standard, SYCL 1.2, and it is. Since May 2015, when SYCL 1.2 was finalized, The Khronos Group added features from C++11, C++14, and C++17, including the ISO C++17 Parallel Standard Template Library (STL).
In other words, you can create C++17 Parallel STL applications with SYCL 1.2.1, single-source, that are able to offload to OpenCL 1.2 devices.
Beyond that, the specification changes also help machine learning. The Khronos Group mentions that Google’s TensorFlow supports SYCL, bringing the framework to OpenCL devices. They want to continue updating the specification in this area, along with Safety Critical applications, such as automotive. They also want to keep updating the standard with ISO C++ features. In other words? SYCL is being adopted, and they intend ongoing support to match.