Decals will be getting an overhaul when lee starts with DX11, currently twisting his arm to consider adding screen-space deferred decal support, should allow for a whole other ball game.There is a small possibility of working with a dynamic texture system, where placing decals for example would reflect instantly on the texture it is placed on meaning, if you place bullet decal, with transparency is should make a neat little hole or big hole in a wall for example.
But the decal system is getting an overhaul soon, no point adding adding some for the interim when it is just going to get changed soon afterwards.
Win7 pro, Intel 2500K @3.7ghz 660GTX 8gig ram 16tb HDD