User blog comment:Gabrielaaloo/Archangel Michael/@comment-2020973-20180518125939

We know he wants to resume his work of purging the world of sin but since the angels are all but extinct he will have to find an army. With Hell no longer having a leader he might decide to take control of the demons and use them for his plan.

Or he might decide to open the cage to bring out the other Michael and use his grace to open the rift to bring in the remaining angels from his world. I know it seems slim they would use that for next season but you never know.