these chapters are going to be the source of luffys future illness/disease or basically almost death that causes chopper to fulfill his dreams it might even allow us to see how the ship runs with luffy on the back burner, I could even see a future time skip post wano just for him to master this form and to make the state of the world believable when they leave wano.
i don't think nika form will become a main stay form in the series, I think fluffy will def burn out this time and it will be a 50/50 chance he kills himself next time he uses it. i could even see the nika form become the inspiration for future forms but the nika fruit is clearly a special parameciazoan hybrid which i think might come from some devil fruit lore we don't know yet.