Shader to RGB in Cycles Eevee has introduced a new node, the Shader-to-RGB node. I find this quite useful for using the outputs of shaders in, say, the factor of a mix node or other such things.
Unfortunately Cycles does not seem to support this node. This is most unfortunate.

How might I replicate this feature in Cycles (at least to support my presented use case)?

(This question involves v2.80)
I'm not 100% sure how the node works, but I think due to the nature of the rendering methods, you will need to bake all of the textures/shading. Here is a tutorial: https://youtu.be/sB09T--_ZvU