I honestly would like her to be available as a companion. Spent the entire game looking for her, and when I finally see my damn sister again after saving the world she just smiles and says "jk lol I got debt to work off". I mean, we already know she is (at least partly) coded as a companion, given she can follow you and shoot lightning etc in the final quest, so it's silly imo that we can't recruit her after finishing the entire thing. Sure, 'tis a bit late, but if you're like me there's still stuff to kill, stuff to overachieve, some stray quests to finish, etc.
As someone already mentioned, after everything we've done, both for Thuram and just in general to amass vast hordes of gold, we can't simply pay off her debt? I threw out nearly half a million at some glorified shrine for The Three's sake. I was so rich by reaching Friguld I didn't have to rob the bank, I could have bought it.