What everyone semms to be forgeting is that most what we know about blood magic is mostly comming from chantry sources and realisticly a lot of it simply can not be true or better said its blown out of realistical proportions because even if half of the chantry stories about dangers of bloodmagic were true Tevinter cud have never endured for 1000+ years especialy in the times of the old empire when bloodmagic usage was a lot more common in Tevinter than it is currently. Another thing to think about is that most bloodmages that fall to posesion we meet so far are basicly desparate people using it as a last ditch effort to save themselves without any real prior knowlidge or training about it.
Also if you guys have noticed it semms that prety much everyone powerfull that has knowlidge of the old magic( Solas-in the dialouge when he asks you about what you think about bloodmagic, Morigan, ancient elves in general dont rly have anything negative to say about bloodmagic they merly view it as another form of magic).
Now dont get me wrong bloodmagic according to what we know does semm a bit riskier for the mage using it compared to regular magic which kinda does mean it is not meant for weak minded and ofcourse there is the potential in it to become power hungry and abuse it, than again whenever there is power avilable theres always potential for abuse.
So provided the next game is going on in Tevinter we should definetly get the specialization back, plus as a side bonus they can intruduce new lore about it from the non chantry perspective in a land where the powerfull have been using it for many centuries without dooming the nation and its inhabitants.
In my opinion if done properly it cud be very interisting to play it and it cud give you options to develop your character a lot like for example are you a resp