If the raid fail as I and
@Buusatan94 point it out(or better our theory*) Law most like get defeated too. In that case either Kaido or one Calamity gonna do it. If the raid working you are right though ^^
@Dark Admiral
Kanjuro isn't really a lose for our heroes. A big tragedy didn't happen yet for our heroes(Luffy and co). In act 3 the heroes get defeated and the arc end with a tragedy/dramatic. In act 4 the heroes attack back and take the win.
Since we move to Wano each act end with a timeskip of 1-2days, act 1 end with a timeskip, act two end with a timeskip. Act 3 most like end with a timeskip too and that didn't would work if we where in the middle of the war. Every timeskip had a meaning, every act end had a meaning, closing a story line. It is a theory but most like Oda end the act 3 in sameway, a timeskip and a timeskip only would make sense if the fight would already end.