The only block I see with this request is to hire back the actress for the voice overs and rewrite many dialog pieces, without counting the fact that many killed her. Fortunately I'm not one of them.
But Bioware seemed to indicate it would not be a major problem, so let's hope for the best.
nah that's easy she could have been saved and thrown into a Kolto tank if you killed her.
That or just reset the quest chain for everyone and then they just have to do it again if they want her to become a companion.