What is the impact of the climax in 'A Streetcar Named Desire'?

I would say that from a realist point of view, the impact
of the climax is that Stanley wins.  The boorish behavior of Stanley, the way in which
he manipulates Stella, and the fact that he ended up raping Blanche are not really
punished through the ending of the play.  I think that one can see that in Stella's
admission of a potential mistake, maybe he is exposed for the fraud he is, but when
Blanche is institutionalized, the realists see an authentication that there is no moral
structure or righteous order within the world.  The realist ending of the play helps to
reinforce that Blanche might have been speaking for more than herself when she attempts
to articulate a condition of a world that is no longer in existence, something that has
passed into the portals of time.  Similar to her childhood in the South, the world in
which justice and fairness exists, where bonds of family and character reign are gone. 
The ending brings this to light.