The Royal Flush being Punchline's henchpeople is a cool idea. Matt Reeves and Todd Phillips should steal that for their films.
Ironically Tynion's creations would suit the Legacies more than Bruce. So putting Harper as the hero antagonist to Punchline works. She also might die as a way to up Punchline's profile because it's her book and DC doesn't know what to do with all the legacies.
But Harper being brainwashed into doing something terrible is a better option.