I think the fights are pretty unpredictable at this point (bar Luffy vs Doflamingo, obviously). Given that the SHs on the Sunny remain out of play for the rest of the arc, we've only got five SHs in play for fights, so you would hope that each of them would get a major and meaningful fight.
So Luffy vs Doflamingo.
Zoro vs Pica looks kind of plausible just based on "Luffy and Zoro are going to the palace, and Pica is in the palace," but to be honest, the positions have plenty of scope for change, especially given the vertical arrangement of all the places people are fighting … plus Fujitora's power being in play.
I'm hoping for Usopp vs Trebol but perhaps more plausibly an interesting Usopp vs Sugar fight. It feels like it could be something like Usopp vs Perona: a tricksy kind of fight against someone who has a really powerful and weird ability.
And then in that case I have my fingers super crossed for Robin vs Trebol. It would just be so good to have that.
On the other hand, I would like to see Franky take on one of the top three. Given Zoro does take one out, he could still take out Diamante. But Diamante still being in the Colosseum does suggest to me maybe he'll actually get defeated there, say by Sabo. Hopefully not, but I think it's a possibility.
I would like to think that other characters being around, eg Bellamy, could play out significantly in the fights, but Bellamy already getting destroyed off-panel by Dellinger has weakened my confidence in that :/
I would guess that some SHs would take out multiple enemies, eg Franky destroying Senor Pink and going on to take out someone like Diamante or Pica.
Oh and I think there could be a major fight against Fujitora at some point, maybe even after Doflamingo goes down.
--- Update From New Post Merge ---
@RobZilla:
Bellamy said he was going to the palace though. Most likely to confront Doflamingo.
when … ? I thought he only said he was leaving the colosseum.