The death of Rip had been teased before on Legends of Tomorrow.
However, the death that Rip suffered in season 3 finale, “The Good, The Bad and The Cuddly” seemed rather permanent.
However, Legends of Tomorrow has already used time travel effectively to have the Legends crew interact with deceased characters, the most notable example being Captain Cold.
It closed out a character that Legends of Tomorrow had appeared to outgrow.