Thx. for the answer.
According to the tag discription, "disuse=yes" "makes sense to use it in case when being "unused" does not negate a feature's primary function." But an aerialway without even cables is far from being usable.
The tag description also says: "For features which can only be returned to use with significant repair efforts, use the prefix abandoned:*=* instead". Thus "abandoned" would be the better choise for this.
Anyhow, having a aerialway in the map which is dysfunctional is very irritating for hikers maybe relying on this arealway and expecting it can be used. Also, since there are no cables, I doubt it has any use as a landmark.
Thus I'm in sting favor of deleting it, esp. since it's a simple line and can be recreated very easily.