You want my theory? You want it!? Alright, I'll give it to you!! Haha =D
I agree that the way you have set it up is the way it will go. Maybe the positions of the Doflamingo Family will be switched up, but it will obviously stay the same.
But if that were to happen, I just think it would take too much time to reach the final fight, then actually finishing that one as well. There's still stuff going on outside, and I think Luffy will join the fray. But if he doesn't and the rest of the SHs and Law have to take care of what's going on outside, then it fits.
So here's my prediction: I actually made this prediction before the recent chapter =D But yeah, so Luffy and Chinjao will destroy the fighting platform, which means that we won't see Block D unfold. First off, who really wants to see that? And that will also further extend the tournament. But after they destroy the platform, the Colosseum becomes a huge free-for-all where Luffy, Chinjao(unless he's knocked out by then), Bartolomeo, Cavendish, Rebecca, Burgess and the rest of the fighters will fight for the Mera Mera. This also gives Rebecca a chance to get the Mera Mera without having to get past Cavendish, and Cavendish himself can finally attack Luffy. With this in mind, Bartolomeo can finally do whatever it is that he also wants to do.