Prediction Pool! Please threadmark this:
Any prediction you have for how things will play out in the Wano arc, feel free to say it here. We'll see if it becomes correct or not. Absolutely no pressure or stakes involved, just bragging rights. (Well, if it's a good prediction anyways)
1. Sanji will take an L - Blackleg-sanji1 WRONG
2. Luffy will achieve Awakening - TheBlackNamekian, Maktokious
3. Hawkins will become an ally - AgentLampshade, Maktokious
4. Drake and Apoo will remain antagonists in some form - AgentLampshade, Ogodei
5. Luffy and Law will team up - NSESN
6. An ally of the Strawhats will die - NSESN, Maktokious CORRECT
7. Franky and Usopp take out two of the Tobi Roppo Headliners - Blackleg-sanji1
8. Momo will meet his sister before Kaido and Orochi are defeated - Reyes, Maktokious
9. Momo will not recognize his sister at first - Reyes, Ogodei, Maktokious
10. Big Mom will bring Pudding - Lotus, Tornak WRONG
11. Hiyori is Perona! - Lotus WRONG
12. The BM Pirates will willingly team up (Big Mom inadvertently so) and help the Strawhats defeat the Beast Pirates, Orochi's forces, and CP0 - Blackleg-sanji1
13. We will see Rox through flashbacks during the Wano arc - Tornak
14. When Big Mom first appears in Wano, there will be singing involved - Lotus, AgentLampshade, Maktokious
15. Sanji will get a W - Stunner11, Ogodei, Lotus CORRECT
16. The BM Pirates will either show up in or change into Wano attire - Blackleg-sanji1 HALF-CORRECT
17. The final fight of the Wano arc will take place where the cherry blossoms bloom - Cantaim (Stelly avatar), Maktokious
18. The final fight will cause the blossoms to fall signaling the beginning of a new Era in Wano. - Cantaim (Stelly avatar), Maktokious
19. The Pirate alliance will take care of Kaido while the Samurai of Wano take out Orochi and both Kaido and Orochi will be taken down in the same chapter. - Cantaim (Stelly avatar)
20. The Marines will not be apart of the fight in Wano and Green bull will not appear in this arc as a fighter. - Cantaim (Stelly avatar) WRONG
20a.Finally the mysterious prisoner is the ex captain of the Rocks pirates. - Cantaim (Stelly avatar) -WRONG
21. Roger and Whitebeard's final meeting place as well as the cherry blossoms that cured Hiruluk will be in Wano and will be a key ingredient in Chopper's goal. - Big One, Maktokious
22. There'll be some type of storyline relating to the animals of Wano that everyone is going to complain about - Big One
23. There'll be an Oden flashback and it'll contain some Void Century infodumps even more-so than usual (this'll be the big thing about 2019). - Big One, Maktokious
24. Wano will turn out to be in a different "place" than normal (might be underwater, in a mountain, inside hollow earth, etc.) - Big One WRONG
25. Kaido's crew will be run out of Wano but they won't be outright destroyed. They'll be back for the final war. - Big One
26. Some type of major death will happen to a main character - Big One
27. Hiyori is going to be somebody we already know about. I think the other retainer, the one we've seen talking to Crocus at the capes, took Hiyori far away from Wano and raised her on his own - Big One WRONG
28. The Reverie is going to turn out to be something very vital in terms of it's connection to Wano despite not being obvious right now. - Big One
29. The Revolutionary Army and the Blackbeard Pirates will be involved with Wano. - Big One
30. OUT THERE THEORY: Kuina and Tashigi are going to turn out to be Dr. Vegapunk clones of Lady Toki. Kuina was rescued by Koshiro in his days in the Revolutionary Army. - Big One
31. Komurasaki is Momo's sister. - Law (If wrong, will acknowledge Lotus' superiority to Katakuri) CORRECT
32. The witching hour boy is the one who stole the blueprints of Kaido's mansion. - Law WRONG
33. Law will "awaken" his Devil Fruit - Law
34. Kaido will die - Law, Maktokious
35. Orochi will suffer an utterly humiliating defeat. - Law
36. The common consensus on Apoo is not going to change.
37. Starting with Ch. 930, Zoro will take no "Ls" - Law WRONG
38. Robin will have an intense and exciting fight - Law
39. Law will help Kid get a new arm. - Maktokious WRONG
40. We'll see time travel, whether it's through a flashback or other means - TheGreatDirector
41. A major unknown third party, not Big Mom or the Marines, will come to Wano - TheGreatDirector
42. An admiral will show up - TheGreatDirector
43. Zoro will lose a sword - TheGreatDirector CORRECT
44. Vegapunk will be revealed and play a major role later on - TheGreatDirector
45. The Fire Festival isn't the climax of the arc - TheGreatDirector
46. Kaido will reveal his devil fruit (and it won't be a dragon one) - TheGreatDirector
47. The alliance will be defeated at the festival - TheGreatDirector
48. Kin'emon will die shortly after - TheGreatDirector
49. Big Mom will show up - TheGreatDirector (CORRECT)
50. Urouge will show up - TheGreatDirector
51. Jinbe will have lost limbs, Judge will be on the verge of death - TheGreatDirector
52. Big Mom and Kaido will form a tentative peace treaty - TheGreatDirector CORRECT
53. There will be a long Rox backstory - TheGreatDirector
54. All of the Supernovas will eventually be on the same side - TheGreatDirector
55. Assuming Big Mom allies with Kaido, she will betray him - TheGreatDirector
56. Blackbeard and Shanks will have a presence in Wano - TheGreatDirector
57. A final war around the whole island, centered on that huge mountain though, will take place - TheGreatDirector
58. Judge will die - TheGreatDirector
59. All the strawhats will get individual fights (including Carrot) - TheGreatDirector
60. Zoro will get a new sword - TheGreatDirector CORRECT
61. There will be more character development for each of the strawhats than from previous arcs in the New World - TheGreatDirector
62. A huge amount of people will fight Kaido, but it'll end up as a 1 v. 1 with Luffy - TheGreatDirector
63. Kaido will die - TheGreatDirector
64. More than one major alliance person will die - TheGreatDirector
65. Orochi will be imprisoned - TheGreatDirector
66. Big Mom will be overthrown by her children after her defeat - TheGreatDirector
67. Pudding will be reunited with Sanji - TheGreatDirector
68. Reiju will take over the Germa - TheGreatDirector
69. Momo will become shogun and open the borders - TheGreatDirector
70. The world government will lose their seastone deal - TheGreatDirector
71. Imu will get a proper reveal - TheGreatDirector
72. At least one other Supernova will be considered Yonko level - TheGreatDirector
73. The Strawhats will head to Elbaf after the Wano arc ends - TheGreatDirector
74. Carrot will not join the Strawhats - tiebreaker
75. The raid suit will be a permanent upgrade for Sanji (uses it more than once I guess) - Lotus CORRECT
76. Queen will have a Scorpion/Ancient Scorpion Zoan DF - Lotus WRONG
77. Sanji will defeat Page One before Drake and Hawkins arrives. - Lotus
78. Katakuri will not come to Wano - TheTyrant CORRECT
79. An important character dies between Ch. 950-960 (no flashbacks) - TheTyrant WRONG
80. Blackbeard invades Totland during Wano arc - TheTyrant
81. During the next act intermission we'll finally see Green Bull properly - TheTyrant WRONG
82. Shanks will be shown during that intermission in the same manner that Blackbeard was in the previous - TheTyrant WRONG
83. Killer dies during Wano - TheTyrant
84. There will be a Kirin DF - Reyes
85. Jack is half-fishman - Lotus (WRONG)
86. A Mink will use Sulong for too long, going feral/rogue and resulting in a Straw Hat having to incapacitate them without hurting them. - Morlas
87. Kawamatsu will reveal himself to be a Mink. - Lotus WRONG
88. King will have a 1.33 billion bounty. - TheTyrant
89. Kaido's bounty will be 2.5 billion. - TheTyrant
90. It will be revealed that one of the samurai is responsible for cutting off Queen's arm. - Lotus
91. Gyukimaku will attack Zoro again when he's distracted - Lotus WRONG
92. Law will die in Wano. - TheTyrant
93. Some shit is gonna go down with the Minks and their Su Long forms and it's gonna be a disaster - Morlas
94. Izo is the Witching Hour Boy - Lotus
95. Big Mom will not fight Queen - daikyu WRONG
96. Luffy will achieve Awakening in this arc - Ogodei
97. The prep time for the final battle will take long enough that it coincides with a full moon - Ogodei CORRECT
98. Either Nekomamushi or Inuarashi will die in this arc - Ogodei
99. Tama and Momo will fight someone - NSESN
100. Chopper will play a role in curing those affected by the failed SMILE fruits.
101. Kaido will die before Act 4 begins - Brock Reiher
102. Usopp or Nami will get captured. - Lotus
103. Ryuma is Kuina/Koshiro's ancestor - Entryhazard
104. Momo will be the one to wield Enma against Kaido. - Imperial Bishop WRONG
105. The broker Jack was supposed to meet up with is one of the Numbers. - edo_kid
106. Each of the nine Scabbards will fight against Orochi's multiple heads. - Blackleg-Sanji1
107. Blackbeard is Xebec's successor like Luffy is Roger's and comes from the same family branch that Whitebeard regarded as "fake D" - Entryhazard
I'll just update and repost this as necessary.