I'm actually fine if we continue seeing Hibiki, the other hero can go die for all I care.
Although Hibiki is being naive in thinking that the discrimination will disappear on its own with time, it isn't weird for her to have that train of thought. Unless she creates her own country or dimension like Makoto, she really can't do much in that world since the Goddess is set on rejecting anything not human. She might have comrades with her, but how many people are really against that discrimination? At most, you find people who are indifferent. She might be able to put the first seed, but I would find it hard for her to change that world in her lifetime and on her own.