I'm not quite sure how the story would work out, assuming it ends in the first dragon being defeated again (maybe it wasn't quite down the first time - well, if you play again, assume that's because a hero must rise because it wasn't quite down the first time)
What am I talking about? I'm talking about not repeating the original story for every single character. Because that story event happened already. Lucains bones were found - why am I finding him again?
No, an aftermath story would be a whole new story to play through, which takes into account the first dragon being defeated. Maybe Lucain went out to check on some troubling rumours and again his mage tower is empty - so you go find him in the aftermath story.
Replaying the first story is jarring? Anyway with me on that? You mash X to get through the dialog, not just because you've seen it before, but because it makes no sense! You DID all that stuff already. Count Dean is DEAD! No, I am not going through the idea that he is a douche, but in the end an okay douche, omg he's gone off and been killed...I did all that. It's over with! Please!
An aftermath story would be events which could be repeated several times. Instead of repeating where formerly dead characters are again alive but then again made dead again, and formerly dead characters who were made alive are back to being dead - but then being brought back to life.
Which would just be more enjoyable - and I think not that super hard to do.