The Blender Foundation and volunteers have been quite busy, especially over the last few weeks. Two major changes that are prepared for Blender 2.79: near-parity between CUDA and OpenCL, and an implementation of the Disney PBR shader.
Aside: A physically-based (“PBR”) shader allows modeling a bunch of common materials, such as plastics, ceramics, metals, and so forth, using parameters that are independent of lighting. This means that you can reuse the same object and material in all of your scenes, and it will behave like we expect it would given the environment. For instance, PBR materials account for conservation of energy, so objects get shinier as they get smoother, but they also look darker off-axis because less light is being diffusely scattered.
While it was always possible to render in Cycles with a PBR workflow, you needed to create your own node setup, which typically consisted of about seven or eight elements connected in a specific way. When this new version lands, you will just need to connect the appropriate textures and colors to their corresponding pins in this node. The Disney-based Principled BSDF accounts for albedo (base color), subsurface scattering, metallic, specular, roughness, anisotropic reflections, sheen, clearcoat, index of refraction, and transparency.
Update (April 21st @ 5:35pm): Blah! I forgot to embed the chart. Here it is.
Image Credit: Blender Foundation
Now we get to “near-parity between CUDA and OpenCL”. According the Blender Foundation, OpenCL can support all features found on CUDA with the exception of correlated multi jitter. This is accompanied by a graph, embed above, showing the RX 480 beat the GTX 1060 in a variety of benchmark scenes. Unfortunately, at the same time, GPU-accelerated rendering in Cycles now requires GCN 2.0 and up, which is the AMD R9 290 and later. Blender will still work on older cards, like the R9 280 or, heck, probably even the Radeon HD 4890, but the final render will need to be done on the CPU.
Blender 2.79 doesn’t have a firm release date, but the code freeze schedule has it expected for some time in either May or June.