If by next-gen you mean very high fidelity graphically then look into modular/tiling PBR textures and using procedural processes like Substance Designer.
Anyways, this would be something more like Tor's modular approach, and less like a "decal" thing. Still the result can look the same as if it would be a decal.
@tyddnroger: I'd suggest using a modular approach as well. Make 2-3 stacks and alternate / randomize the use of those stacks for simulated realism. Cheers~
If I have a scene that is made of many modular objects already, is there a quick way to take 1 of each of these instances and place them in their own XRef File?
I made a tutorial on modular pieces in my artsation challenge tutorial series, it would probably be applicable to building fantasy environments :) https://youtu.be/xC0uL_QQWeY