A great advantage would be, if Substance could IMPORT ALREADY EXISTING MATERIALS (shaders) from other applications (Maya, Max, Blender, Unreal...) in order to work on them and to refine them.
Right now everything has to be created from scratch or maps have to be imported manually.
Quite often a textured scene is already existing and the user only wants to add grunge maps or test new materials on top.
A kind of EXCHANGE PIPELINE to different render engines for asset reworking / refining.