I've been thinking about the whole "dragons are resistant to the Taint" thing. Now, ofc this could be attributed to "magical dragon blood", but why would they need to be resistant in the first place? Things usually become resistant/immune to... things... that are a danger on an every-day basis. Meaning, the dragons must have been exposed to the Taint for a long time to develop their resistance? The Taint, the Taint everywhere
Just a random crazy thought 
In theory, dragons are resistant because blight is essentially a battle of Will: whether its Song is able to overpower who and what you are. ...which seems to be true for just about everyone and everything, given enough time. Dragons (and other similarly old or strong-willed entities) hold out longer because their own Song is strong enough to compete for a while. Similarly, Grey Wardens' intense sense of duty and purpose, reinforced by the rest of the blood magic ritual, allows them to hold out longer than most.
I'm still trying to wrap my mind around how Andruil was un-lyrium-ified back in the day, though. If we start with the assumption that collaboration with June progressed from simple augmentation until she was essentially a red lyrium golem with Andruil's OGS inside, were they forced to yank her 'soul' out wholesale, cleaning it Archdemon-style? Or can we assume more finesse with Falon'Din / Dirthamen involved- redirecting her back into an untainted body?
Either way, it's a bit concerning that there might be an extremely advanced and powerful empty red lyrium golem-vehicle sealed away somewhere, just waiting for another powerful spirit to jump in and take it for a spin. @w@