Vic,
Someone whose fate is unknown is a person for whom no information is available as to what became of him/her during the war, according to one or more sources. Someday, somebody may find some information - at that time, we will know if the person survived or, if a victim, where the person died, At that time, we will be able to move the person from "fate unknown" to the appropriate category - either Survivors or Victims at xxxx. Actually, it is very likely that the people in the Fate Unknown category died at one of the camps or ghettos, since nobody has yet found any evidence that they survived.
If a researcher only knows a person was a victim - or if they are looking for a person and try Survivors, then try Fate Unknown, and don't find the person, perhaps it would be good to have a single place where all victims would be so that they could find the person there, instead of having to search each of the 30+ (and still increasing) camps and ghettos individually.
I am not at all knowledgeable about this stuff - I'm very new to genealogy - so I have no way of knowing what the best structure would be. The change I'm asking about here would bring the Holocaust category structure parallel to the way some of the place categories are structured.