Chiming in to ask if there has been any significant development on this front?
I don't think it can be reasonably asserted (at this point) that the available solutions for height blending in 3ds Max / Corona Renderer are contemporary with respect to other render engines.
Looking over the provided examples, the solutions that exist for procedural height blending in 3ds Max / Corona Renderer are very complicated, cumbersome, and really echo a much older framework for shading / rendering, but it seems like the major obstacle is actually the implementation of displacement blending across materials in a layered material.
Is there some plugin or set of tools that operate within 3ds Max / Corona Renderer to facilitate layered material blending with displacement? To be sure, vertex paint is not a procedural solution and would not be appropriate for texturing multi-layered materials across a large surface.
P.S. the original post is from 2016!
Some day, in 5 years, where GPUs will be all powerful, real-time antialiasing and GI on same level as offline raytracing, it will be game over :- )