Well like I said, it is meant more to offer an easy way to start with OpenCL, a technique that is still very useful and has not gained enough traction IMO. I agree that basing an entire plugin on OpenCL might not be the most future-proof decision, but for things like prototyping I think it still offers the quickest iteration/experimentation times (Vulkan is way more explicit and verbose). There are plenty other areas where OpenCL is useful, while people might now be discouraged by the setup required (I know I was when I started). The example will give them some handles and offers one-click compilation with the Projucer.
Besides that, Vulkan/Metal/TheNextBigThing will still require an OpenGLContext to render stuff into JUCE components. How to create a persistent context has been asked several times before and I think I’ve found a way, but I want someone to check if I’m not doing something dangerous/stupid. If not, you could use this context to render using any GPGPU technique that your heart desires, including most likely Vulkan on Mac (through MoltenVK).