There are several fan theories and rumors about the upcoming chapters of the manga series "One Piece" posted online. Fans are hoping for the series to reveal Luffy's fifth gear as he faces Big Mom's second son and one of the three sweet commanders of the Big Mom Pirates, Charlotte Katakuri. 

The on-going arc of the series is titled "Whole Cake Island Arc," with Monkey D. Luffy and the Straw Hat Pirates' members fighting the Big Mom Pirates.

In chapter 881, the Straw Hats survived Big Mom's wave homie and are now sailing to Cacao Island to rendezvous with Sanji, Chiffon, and Pudding. Meanwhile, Luffy is still stuck in the Mirro-World created by Charlotte Brulee. In Chapter 882, Luffy is still struggling in coming up with combat tactics to counter Katakuri's mochi-mochi power and his trident, Mogura. In a desperate attempt to broke-free after being wrapped by Katakuri's mochi, Luffy prepares to activate his fourth gear.

Viewers have been exchanging plot speculations about the current arc of "One Piece." Chapter 883 is scheduled to be released on Oct. 30 and most theories are about a heated battle between Luffy and Katakuri.

After discovering that his crewmates made it out alive, some fans present the idea of another awakening turning point for Luffy.

 In a Reddit forum, people are suggesting that Luffy will repeat his water move against former Shichibukai, Crocodile and his Sand-Sand fruit. In chapter 200, Luffy made use of water to be able to inflict damage to crocodile without using Haki. According to a new theory, Luffy will use his blood to apply moisture to Katakuri's body in order to hit him.

Going back to the fifth gear theory, some fans assume that it would be too early for Luffy to unleash it, since fourth gear was just recently revealed. In the case of other theories, Luffy will show a different variation of the fourth gear. The latest gear also takes a devastating toll on Luffy's stamina and it seems impossible to pull-off fifth gear in his current condition.

In a different forum, long-time fans are hoping for more screen time for Jinbei who helped the Straw Hats escape Big Mom's attack. 

There are no official spoilers so far for chapter 883 and fans are focusing on an upcoming war between Luffy and Emperor Kaido. One of the biggest fan theory indicates that Luffy will die after clashing with Kaido and Trafalgar Law, his ally, will use his Ope-Ope fruit to resurrect Straw Hat by sacrificing his life.