After the action of the play, as in comedies, we return to a similar stasis as where we began. The Duke returns from his escapades as a friar, pardons Claudio, and proposes marriage to Isabella. His reestablishment as the ruler of Vienna is what brings the play back into the stasis of a functional society.
Although Vienna in the play will continue to exist with a morally-poor society, this is the stasis with which it can continue to exist. The establishment of Lord Angelo as the temporary ruler throws out of balance the delicate nature between the desperate pleasure seekers and the saint-like religious folk, leading to the action of the play. His removal from power brings back the delicate balance between the two morals and groups.
by Paul Kappel
I’m not confident in this.