Hidden names.

[Denash]

This would be awesome in some cases. But also lethal in others.

I don't know how closely NOTCH guards modification to MC but perhaps a reduction to the range you see the name? Knocking it down 50% would do.

won't just stumble upon your city by seeing your names and digging/searching for the entrance.

A constant fear, especially if you're in a chest hide out.

Once on a different server I heard what sounded like player injured sound effect coming from top side... I was in an underwater base at the time so it was worrying to think I had been discovered. I went up to find a nice neat pile of stuff floating in the water... I guess someone had heard my burning fireplace below and decided to dig but forgot to breath. He had a nice pickaxe!