The dark one arc would actually be about the dark one. I think Emma being the dark one was an interesting way of going about it, but Hook would not be part of it. Neal would still be there and it would be about how Neal knew what it was like to have a father as the dark one and now Henry’s mother is the dark one. That Belle knew what it was like to have a love interest as the dark one and Neal’s love interest is now the dark one. Emma would have said all the things she has ever said about the parents that abandoned her to Snow and Charming. Emma would state all of the mistrust she initially felt towards Regina at her. It would be about Emma talking to actual Rumpel about being the dark one and what he has lost from that and how his desire for power has messed up his life. It would not be Emma talking to a fake Rumpel in her head. Oh yeah, i forgot. Rumpel would no longer be the dark one, so we would see him interacting with Neal, Belle, and Henry as not the dark one and they would be talking about all that. The dark one mythology, for me, is easily the biggest like plot point mistake that was made.
Season 5 started out so strong. I agree, they really botched the dark one mythology. It could have been so cool, so incredible. Should have left Hook out of it. Should have actually made Emma evil. Loved introducing Merlin. I even liked Arthur being an antagonist. When he forced that guy to kill himself in the storybrooke jail cell….my goodness. It had so much potential. And they ruined most of it. The storybrooke part of season 5A was so bad especially. Like Emma keeping the sword in her basement. Not being able to pull it…and Merida training Rumple to be a hero to pull it……it was disgustingly awful.