To me it seems like it'd only get more visible as it gets more normal, or at least more predictable.

Remember back in the early 2000's when people would photoshop one animals head onto another and trick people into thinking "science has created a new animal". That obviously doesn't work anymore because we know thats possible, even relatively trivial, with photoshop. I imagine the same will happen here, as AI writing gets more common we'll begin a subconscious process of determining if the writer is human. That's probably a bit unfairly taxing on our brains, but we survived photoshop I suppose