Agreed. I mean it is possible that if this series got picked up for season 2, I think the plan was for them to return, but with Ray Stevenson passed away, we probably won't get more about him. I don't think they will recast, but will just kill him off screen.
Now we may get more Shin backstory, if there is a season 2, or on some other show/movie. At least I hope so.
Also, how weird is it that Hayden Christiansen is now about the same age as when Vader died in ROTJ?