It's entirely the cost/perf of access to the larger amounts of VRAM that keeps rendering on CPUs now. GPUs are strictly better in almost every way for rendering

It's entirely the cost/perf of access to the larger amounts of VRAM that keeps rendering on CPUs now. GPUs are strictly better in almost every way for rendering (We could have some arguments about technical precision, FP calculations, etc. but with modern cards these arguments are largely semantics, you can have output that is accurate to the level that any human watching for entertainment purposes will not be able to determine any physical inaccuracies that arise from a GPU render vs. CPU.), except the need for large amounts of VRAM being quite expensive at current. But that's already been changing, and we are seeing studios moving to fully GPU based pipelines. Wylie Co, who are a major visual effects company (Dune part 1 and 2, marvel movies, the last of us, a bunch of others) are now a 100% GPU shop. The trend is towards more and more GPU rendering, not less. With AI providing another strong incentive towards increasing the amount of VRAM on GPUs, I don't see any reason to believe that trend will reverse.