I’ve seen many speculations regarding the fight of Luffy and Katakuri which can be read in the last 2 pages of chapter 892. Many people believe that Luffy acquired future sight and the panel where he got hit by Katakuri’s attack is only a vision. Well imo it is real, I believe Luffy actually got hit by Katakuri is now heavily wounded. And as the title suggests, I believe that wound will trigger a new power up for Luffy.
But how is it going to happen? Well if you noticed the wound that he got from Katakuri’s attack is near his scar. So what will happen is that while looking at his wound, he will have a glance on his scar which he got from Akainu. Then Luffy will start to have some flashback of what happened in Marine Ford and the death of Ace. He will also remember that one of the reasons why he failed to save Ace is because he is too weak.
He will realize that if he give up now, the same thing will happen again. People who are close to him will be in danger. This will give Luffy the strength to stand up. This will trigger Luffy’s new power up….. 
Ok so you maybe asking now what kind of power up he will get. Well I believe his memories of Ace will help him create a new technique.
And that is a Flaming version of Gear 4th.
Uuummm… I actually made a theory about this before. I mentioned there that Luffy will combine his G4th with Gear 2nd. This technique will give him more speed which I believe is the only way to defeat Katakuri. As you know what makes Katakuri a very strong opponent is because of his future-seeing observation haki. Even though Luffy’s CoO (Observation Haki) improves a lot, I still believe there are still a huge difference between their CoO. So imo, the only way to fill that gap is with speed. Luffy needs to be so much faster than Katakuri for him to be able to land a hit.
Ok… so there’s still the problem of Luffy’s wound. Don’t worry there’s a way to close that huge wound and stop the bleeding. The method is called causterization. A medical technique of burning a part of body to remove or close a part of it. How will he do it? Well using his flaming fist
Foreshadowing
Now while examining chapter 892, I found a possible foreshadowing that Luffy will have a flashback of Ace. ^^
Doesn’t it remind you of something?
Or much better this part
Coincidence? Well I tried to further backread Marineford Arc then I noticed that many panels between the fight Akainu and Ace in chapter 573 has resemblance to the panels of Luffy and Katakuri fight in chapter 892.
More interesting thing is that Ace and Akainu’s fight has a similar circumstances to Luffy and Katakuri’s fight. Both of their Df’s have similarities. Both Luffy and Ace got overpowered by a much stronger kind of df.
And now here are the panels that have resemblance to each other from those pages.
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2.
3.
4.
5.
Having these many panels that has resemblance to each other, I don’t believe this is just a coincidence. That’s why as I stated above, this is a clue or a forshadowing from Oda. We all know that Oda loves to give a forshadowing. Remember this cover page that forshadows Ace’s death
Additional: I just noticed this, in chapter 574 titled “The death of Portgas D. Ace”. You can see the word Mogura.
Remember Mogura is the name of Katakuri’s weapon 
. Another possible clue?
*Theory by jinz
