>>535093064
actually I need to revise this. We actually have seen unique weapons skins that change the model of the gun, not just the color. In this image the top right tan gun has a unique skull receiver as well as a unique skeletonized grip with multiple finger grooves, so it seems like the developers aren't just making color changed only skins

I believe this further reinforces the theory that option 3 is the likeliest outcome.