I can see a few possibilities in there for this to be tropeable:
1. A wider definition that doesn't account for any specific type of creator input: Actor for an already absent character dies; the character is perhaps stated to have died, or is treated as still alive, or is simply not mentioned again. This would probably be more of a bit of trivia than an actual trope, though, since it is simply a type of Real Life
event that affects the possibilities of the fictional universe.
2. A narrower definition, where the input of the author(s) is crucial: Actor for an already absent character dies, but the character is still treated as if they were alive, even though there's no chance for them to return (short of The Other Darrin
, or similar tropes). This would count as a trope in my book, since it's a conscious decision on the part of the creator.
If there's a problem with the name, what would you change it to? The current one fits in well with existing snowclones, and the only alternatives I could think of would be of the highly prosaic
variety, e.g. The Actor Dies After The Character Left