It'll be interesting to see how things go from here. Realistically speaking, the so called element four aren't too far above them all in strength. They beat one, another was sniping them so caught them off guard, a third we saw but hasn't fought, and the fourth is tricky to fight but might be easier to beat with a different matchup. Even her older brother is close enough to Shiki for him to win. The tricky part is the boss himself. The framework is possibly there but I doubt it'll be an easier fight when he's normally outclassed.