Measure for Measure: staging silence

At the end of Measure for Measure we have one of Shakespeare's most enigmatic silences. During the play, Isabella, a novice nun, has been attempting to secure her brother Claudio's release from jail on charges of fornication. She has been accompanied by the Duke of Vienna, who has been disguised as a friar, apparently in order to test the virtue of his deputy Angelo. The friar-Duke manipulates all the characters so that the final act sees them acknowledge their failings and gain a troubling sort of punishment/restitution in a series of marriages. It's a dark comedy in which the nagging doubts we may often experience at the multiple marriages typical of the genre are blown into a profoundly unsettling conclusion.

At least, they may be. The ending of Measure for Measure gives us the option. The Duke's final piece of tidying up is to propose marriage to Isabella. There has been no previous textual evidence to suggest that they might be a romantic couple, other than the specious coincidence of their matching friar-and-nun outfits, which, even by Shakespearean standards, is not much of a basis for marriage:

Two lines later, the play is over. Isabella does not respond, either in words or with an action indicated by the stage directions. Does she accept the duke, or not?