Saw this on Reddit.
What if Kizaru's justice is "unclear" because he doesn't have a dream, and that's why he wants to fight people that have duty/dreams (like Sentomaru).
What if Egghead ends with Kizaru getting a dream and him joining the Strawhats as the 10th member.
Blackbeard 10th commander = Kuzan, Strawhat 10th commander = Borsalino.