So, if I go wondering the wastes of fallout or the mountains of skyrim, and I kill everyone will the world be empty or will they respawn elsware? Or will the world slowly repopulate with new faces?

As I recall Ponies without names (like Guards) will respawn.

What about citizen ponies that you chat with

As far as I know, those ponies won't respawn.

What about essential ponies? If you're not on PC you can't use the console to remove the essential tag.

Well, unless you're playing Morrowind. There are no essentials there.

All non-essential named ponies will be dead permanently. Otherwise everthing else respawns. It's really to keep you from killing literally everyone and getting bored.

It'd still be boring... So I should consider all wasteland ponies lives valuable??