Split: The Artifact

I looked through the examples and this trope seems to be detailing two different things: Character and premises that remain after a show has outgrown them. I think a split is in order between those two types of examples; something like Artifact Character and Artifact Premise or Artifact Gimmick or something among those lines.

bump

I think it's fine as is. In this particular context, characters, premises, and gimmicks are pretty closely related. It's all "stuff that made sense at the time, but maybe doesn't now."

But in the case of characters, wouldn't it just be a case of Demoted to Extra?

Not necessarily, just a character whose characterization has been left behind as the show or series has changed in tone. Examples are The Undertaker from the WWE, who's a call-back to the cartoony gimmicks of the early 1990s, and Jadzia Dax from Star Trek Deep Space Nine, who had the personality of a Star Trek The Next Generation character in a Darker and Edgier show, though that was likely intentional. Both are major characters who could be considered Artifact Characters.

The problem is that all the split categories tend to be redundant. Yu-Gi-Oh has stuff that qualifies for all 3 originating from when it wasn't about Childrens Card Games for example.