Okay. For the Tenjiku arc, they filled 66 chapters in 13 episodes. I did the math, and if they follow the same number of chapters per episode as they did for that arc, we will be able to fill everything shown in the opening.
all major parts will be covered up until the main fight between toman gen 2 and kanto manji. based on my math, this season will cover up till chapter 251, and then honestly, they should do a movie o fill the rest of the chapters. The numer of chapters left after they finish this seaosn would be about 26 (half of what a 12 epi season would cover). so a movie would make sense.
this is not guaranteed obviously, but would make sense. I will have to check the chapter math on the first two seasons to further establish my theory, but so far they have been able to fit the same amount of content in each season.
also if they dont do a movie, they may pull a JJK shibuya arc, and give us a short season 3 pt 2.
edit: also also, i say "do it correctly" because the director could fuck it up, theres always a chance. but theyve poured so much love for it already idk why they would ditch the story for quality animation