Oohh honestly i think they kinda did that already abt the breaking the promise bcs 1. Minku already kinda did after Suipuri disbanded and break their promise. 2. aboyt making a new one too bcs at the part of where their revue ended, Minku's promise being renew from "becoming the best idol in the world" to "becoming the best stage actress" and thats how they become rivals because they're now both aiming for the same thing(?) But i guess its a bit different because it's only Minku's promise that was changed. But you knowww, the point of their promise still remains(holy shit. Title drop /j) because they both promised to become the best in the universe too...

Though other than that, ARGH. I LIKE THAT IDEA.. but oohh if we put a little more thought in it. Imagine that one of them gives up for being a stage girl because looking at thw recent game story events, Kuina felt like she's getting left behind.. so like, that could be one of the issue that might break their promise because one of them is slowly falling apart and might give up someday...