I just thought of something else that's been bugging me as I've read theories on who Sabo is going to fight. If he's going to fight Trebol as some have speculated, then why in the world did Oda make Koala go the palace and Sabo stay behind!? The last time we saw Sabo and Koala together was in Chapter 760, where Koala was telling Sabo off for fighting Fujitora, then in Chapter 768, Sabo helps out civilians while Koala rushes to the palace. In this chapter, we learn that Koala has just arrived inside one of the castle towers. If Sabo was going to fight Trebol and help Luffy, wouldn't make more sense for Sabo and Koala to switch places? It's weird. We can see in this chapter and previous ones that Sabo gets worried about Luffy's safety. So why didn't he go directly to the castle and have Koala free the gladiators? I originally thought Sabo decided to just let Luffy handle things on his own, but this chapter proves that's not the case.
It could be just a simple way of building tension, but there's something off about that. Sabo's all the way at the Colosseum, which means unless he can fly like the Human Torch, (which would actually be awesome), there's no way he'll get to the palace in time before Luffy fights Doffy, and Trebol's right next to Doffy. If Luffy then fights Doffy, who's going to be defending Law? We know Law's not likely to be dead, but he is likely to be too injured to fight and needs healing from Mansherry. Would Luffy fight a 2v1 battle and have Robin and the dwarves heal Law? But if Law gets healed, would Sabo still be needed at that point? We know Law can take on Trebol relatively easily, so where's the need for Sabo?
And if you look at it another way, Sabo fighting Trebol means that there's would be no need for Law to get healed … so does Law get healed after the battle? Mansherry's right nearby, so it can't be that, she was locked in the castle for a reason. And again, unless he can fly, Sabo's not going to get to the place and fight Trebol right away. So unless Trebol just sits there and does absolutely nothing but watch Luffy fight Doffy, some one is going to have to save and heal Law. And, again, if Law get's healed, why do they need Sabo? Something about the speculated sequence of events for chapters in the future don't add up. I think I'm missing something here.