Technically RG Sylvanas doesn’t need a redemption arc, she was a hero that fought and died to defend her people. She’s a hero. I would like to coin the term Nuvanas, but it doesn’t quite fit.
The Banshee Queen on the other hand. Well, Zovaal basically did a kill steal. There will be no redemption for her; she’s gone. Hopefully he shot the mustache twirl out of her and left the part that I enjoy about her character.
I hope she sticks around for the entirety of WoW.