Why i think it should happen? Because it'd be cool
Like everyone's already said cross guild should raid impel down in order to get free labor aka doflamingo. It'd also allow them to save bon chan the π and a good amount of strong fodder
We know perona is trying to meet up with moria so maybe she'll try and convince him to join since she knows mihawk. Idk how but if theirs a way to get moria back to his prime it needs to happen