The brackets aren't complete, but based on what I see actually listed on the IBJJF website, I've made some predictions. Right now, a ton of notable names are not laid out in the brackets - everyone from Lovato to Claudio Calasans to either of the Mendes brothers, so I will try to find time to amend these predictions as to how the bracket will play out whenever the "world championships" brackets are actually laid out. Professional tournament and such. It's not like the tournament is only 3 days away from the black belt division beginning or anything:
Brown Belt - expect the Miyaos to close out at weight, Gianni to win his division, and Keenan to win at both weight and absolute.
Rooster/Galo - Bruno Malfacine. Without Gui or Caio standing in his way (both of whom he has beaten), I don't see any names that will likely challenge Bruno. Actually, I've just read Caio will be in this division, so I'm calling another Rooster Finale between Bruno and Caio, with Bruno just a bit too strong for Caio and squeaking out a points win.
Light Feather/Pluma - Samuel Braga will win through his side of the field, dpending on where Gui ends up competing in the bracket but I don't think Braga has what it takes to top the mercurial Gui.
Feather/Pena - Expect Cobrinha to come through to the final after winning his field and facing Theodoro Canal in the semi-final, after beating G. Goncalves Martins in the quarterfinal. On the other side, I see no reason why Augusto Mendes won't come through to the final and they will rematch in their battle from the Abu Dhabi Pro Trials. Tanquinho has said this will be his final Mundials, win lose or draw, but I'll peg Cobrinha's will to win another title to eke him out over a Mendes last name other than Rafael. Again, with the bracket incomplete, how it plays out will depend largely upon wherever Rafael Mendes finds himself. That being said, Tanquinho has always stylistically done well against Rafael Mendes and I could actually see him beating Rafael Mendes. You read it here first!
Light/Leve - Langhi will top Mendelhson (one of the US's best shots in the division and at black belt to do well or medal) and get to the final where he will face Zak Maxwell (the other best US competitor to nab a medal or become a world champion). There are times when Maxwell looks amazing and other times when he has struggled against long-time black belts. I think Magid Hage will represent himself well and he did in fact catch Maxwell (along with Clark Gracie and another black belt with his now famed baseball choke at the abu dhabi pro trials in San Diego), but it remains to be seen if Magid Hage has more up his sleeve than what was his unknown baseball choke. I think Langhi tops Maxwell in a very tight final and wins his second world title in the Gi. But between the likes of the above and guys like Roberto Satoshi and JT Torres, it is exceedingly difficult to call this bracket or how it plays out. Each and every match has the potential to end either way with guys like this competing. It remains to be seen how Torres handles his move to Atos (he accounted himself well at the Copa Podio fighting well and competitively against the inimitable Leandro Lo and others in the division and accounted himself well at the Pan Ams most recently).
Middle/Medio - Otavio is going to lay waste to his half of the field in relatively short order. He has looked crazy dominant at both weight AND absolute this year and at the various IBJJF's and I don't see a single name on his half of the bracket I think will have anything for him. Other than Kron Gracie (not listed I assume due to Metamoris II obligations), I haven't seen anyone with the kryptonite to the world champion super powers of Otavio, who if anything, looks even more dominant this year than last year leading up to the Mundials.
Medium Heavy/Meio Pesado - A division I admittedly know little about, Romulo will (pending his knee injury from the match with Galvao at the Abu Dhabi Pro) win his half of the bracket and face Abmar Barbosa in what will Definitely be an exciting match with Romulo pulling out the victory as long as he's not fighting seriously impaired by the Abu Dhabi Pro injury.
Heavy/Pesado - Rodolfo will punch his ticket to the final by beating Yuri Simoes in the semifinals, and will then beat either Nivaldo Lima or Alexandre Ceconi de Souza in the final.
Super Heavy - Super Pesado - With Leo Noguiera out with a knee injury, I'll call Bernardo Rocha on the strength and preparation of his work with Alliance to take home the world title.
Ultra Heavy/Pesadissimo - Buchecha. Igor Silva and Vinicius will fight it out on their half of the bracket in the semi finals, but Buchecha will come out on top at weight and in the absolute.
Some other bloggers predictions at I Fight in Pajamas - HERE and Bishop BJJ - HERE.