Toland is kinda forever in limbo, but that's is basically his character. But I wouldn't complain if some lore was thrown his way. I do agree the Scorn and Vex have taken a backseat to all the other enemies. I am glad the Taken at least got some answers now being under the Witness's control. The Scorn got a little touched on in Season of the Seraph, with Eramis seemingly turning her followers into Scorn. Which may imply she gas connections to Fikrul, either through the Witness or not. As to my knowledge, and I nay be wrong, the Scorn also currently fall under the Witness's control similarly to the Taken. The Vex a tricky because there's not a singular force driving them. They are a borg-like hive mind entity who's only motivation is survival, in a way they're the most animalistic of Destiny's enemy races. I would however like to see some development of the different sub-divsives within Sol. As well as the anomalous individual Vex, who demonstrate unique traits or have absorbed human personalities.