Four chapters from now, Wano will officially be the longest arc in the manga, and it won’t be over by then or even shortly thereafter; Oda has also been fairly vocal about sticking to his five-year plan for ending the series, so why does anyone still think there’s a round 2 in the works for this war? The raid won’t fail, Onigashima won’t crush the Flower Capital, there won’t be a timeskip in between what we’re seeing right now and Kaido’s eventual defeat...once this particular battle is over, we won’t need Big Mom singing to let us know it’s truly finished, it’ll be unequivocally obvious.