Personally I'd like a revision of Lindir. I know that he enables the Noldor mechanic and there's a place for him in that build. But I'd have really liked to see him be a minstrel and have something to do with songs. His name means "chant" or "sing" in sindarin, so it seems as though he should have done something with songs. I think a lore version who was basically Damrod for songs would be fitting. It'd really help out the whole song framework in the game. Bringing love of tales and certain songs into greater viability.
As has been noted, Radagast is about over due for a rehaul. Changer of shapes and hues is a broad description of him, and in this game theres a lot of potential for that. As Yavannnas Istari tied to both plants and animals I don't think it would be contrary to his character to have some sort of interaction with Ents. After all, how can a disciple of Yavanna who existed since the beginning of time not know about the guardians of the trees? Change of color and of hues could have implications for sphere changes... as Istari are non-sphere entities in the game I'm not sure how that could be simulated but I don't believe it would be too much of a stretch. Maybe more of an emphasis on his spell-work may be in order. An asfaloth-esque benefit for Radagast but still viable with other Istari?