"He who climbs highest...

...has the greatest fall" (V.iii)

Nice line. Who I guess this line would apply really only to Lussurioso, since he is the only character in the play that truly makes any social gains without disguising himself (like Vindice). Does he deserve what he gets? Probably, but I think that the real message of this play comes through the fate of Vindice and Hippolito, who have a special reservation in the hall of revenge-seekers being perhaps the only two who must answer for their crimes despite having put the new power structure into place. I'll say that they deserve it, and the moral lesson here is that nobody wins in revenge (glib though it may be). I think that it's interesting though, considering they're completely unapologetic at the end, and ultimately they succeed in the killing of the entire duchal line (which quite honestly felt way too rushed and the subplot between Supervacuo and Ambitioso was altogether useless at the end, since they jsut come on stage and take turns killing each other).
I like the opening of this act. It feels really really classical. Characters enter, make remarks to each other about the old Duke being dead, making occasional asides the audience about how they're not actually sorry about it, and then exit, one after the other, each given the chance to say one last thing to audience. It signals the wrapping up on the plot, each of them stating directly what they are going to be doing in the next interlude between scenes, then exiting to do it, and then when they return, the Dutchess has been exhiled (considering, unlike Titus, this play would never allow a woman to die on stage) and everything in the play has been settled. Of course, from there, it's time for everyone to die. A triumph of dramatic structure.