She never turned bad. She might have some spite in her but I believe that everything that she has done is for her kin who Uther slaughtered. She just want justice for her people and I think she wouldn't be the Morgana we have today, if Uther hadn't created the Great Purge. Sorcerers wouldn't need to live in fear and neither would Morgana. So yeah, if somebody showed her what Arthur was destined to do she might change. Or darkness will have fully consumed her, and there was never any hope for her.