Yes, it is unfortunate that Cycles no longer supports OpenCL on macOS. There has been talk in some of the Blender groups about porting it to Metal (Cycles was designed from the ground up to support multiple platforms like OpenCL and CUDA), and they were speculating that it could be done by a skilled developer in 3–6 months [0]. Hopefully there are enough Blender users on Mac to justify this effort. Anyone here have ideas about organizing / funding this?

In the meantime, check out AMD ProRender [1]. It appears to be a viable alternative to Cycles for most things and can run on Metal on macOS.

At any rate, for more substantial renders, I strongly recommend cloud farms. You can make your own using spot instances to save money, and fire up more servers to get your render done more quickly. Getting an overnight render done in less than an hour (without tying up your workstations) is super helpful since it gives you more freedom to iterate. This kind of task (where you need a huge amount of processing power periodically for specific jobs) is where cloud computing really shines.

And there is also Eevee, which is not a Cycles replacement, but I believe it is fully supported on macOS.

[0] https://lists.blender.org/pipermail/bf-committers/2018-Decem... [1] https://community.amd.com/docs/DOC-2183