I deem this feature to be very important for landscapes creation, and i hope other creators would agree with me
Basically, this feature would work layering shaders using an image based blending mode.
This works pretty much like Maya's Layered Shader, where we can use the RGBA channels of a "splatmap" as alpha value in the layered shader, to blend the different shaders together. This gives us the ability to keep image size low by tiling the actual shader, while the engine lets the splatmaps manage how they interpolate on the surface. Using a RGBA image ensures up to 5 shaders (the base shader doesn't get transparency); Base rock, sand, soil, grass and snow would perfectly fit in such description. Each shader contributes with their normal and detail normal, but it would be even more cool if the layered shader itself could get its own normal map (for the very big and general shape detailing)