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It's basically Death by Adaptation or Dies Differently in Adaptation
Can be Not His Sled if their prolonged survival has radical implications even if they do end up dying later on.
Say, Bob was Alice's I Let Gwen Stacy Die in the original continuity, but in a What If? story he survives to die in some mundane way later. This still ends his role as first love interest , but creates rippling changes in events down the line as Alice never had the moment that made her reconsider her reckless approach to heroics.
Edited by Scorpion451
A character who is Doomed by Canon is in a situation they would possibly die in, but no, the authors decided to pull this twist and let them die later.