I feel like the 4 leaders thing is just going to be underwhelming, because you'll wonder about their infrastructure, like what gangs they control and their own castle, and I doubt the series will have time for that, without it distracting from the momentum of the story. I think other characters like Ziming and Tentie will be easier to introduce because they would have more clear roles, Ziming brings Xiuying back in the story, and could be a partner in Lan Di's side of the war, and Tentie is Sun's next obstacle, but they're just examples.