Now I'm no mapper, but I do more or less understand the basic principles of how they're made. The question I have to pose is this:

-Make the relief map which determine map heights a uniform color (ie make it flat)
-Find a tileable worn paper texture and overwrite all of the terrain files.

Very simple, but would something like that work? Obviously the water textures would be the same, but I imagine you could apply the same process to that.

The only real flaw I can think about this would be that the map would somewhat empty without being able to have the written components of the map (like drawn mountains, or province names).

I guess I'm just wondering if this is a viable option. I'd be interested to see the results of something like this.