Hi Jeremy. Ok everyone! Don't respond so matter-of-factly. I believe in art, and therefore I attest to the beliefs of freedom of interpretation.
My Belief:
Caroline has died in some way at the end of the piece. Now, as the piece does deal with symbols, metaphors, etc., it is up to interpretation. Here are examples to prove my point, though there is a small chance I might be wrong

:
"Lot's Wife" Functions as the end to Caroline's anger and life. Just like Lot's wife, in the end, she has died. The stage directions state that the children and Caroline are going to church, and that at the end of the number they come on stage in their church garbs. I infer that they are going to Caroline's funeral. Emmie enters, "sullenly", carrying her mother's clothers, and hands her mother's clothes to her mother. They all run ahead, and Caroline follows, almost like a funeral march.
Following this is the song "How long has this been going on?" A question many ask after suicide, wondering how long the depression had been taking place. Not to say Caroline killed herself. They sing of salty teardrops becoming one with the ocean. She has metaphorically drowned.
Caroline appears in her maid uniform, as Noah is in bed. This is the only way Noah ever saw her and the only way he would remember her. This is how he conjures her in his head. Noah leans out the window to speak to Caroline, who definitely did not live right outside of the Gelman house.
He asks if they will talk again. Caroline says
"someday we'll talk again. Just gotta wait." Screams death to me.
The moon then sings:
"...Unsuspecting bring us these secret little tragedies."
Noah asks what it is like underwater. Caroline could not afford to be buried above the ground, and there is no underground in Louisiana but their basement,so the ONLY reason she would be underwater is because she has been buried.
She says that underwater is like the sound of her mother's instrument. Which hasn't been played since her mother's death.
Its like "sleeping with the lights out"
She proceeds to speak about what happens when you "stop breathing air you get oh so calm" and how you miss the sun, which one wouldn't see when buried.
The song ends. The only stage direction is that "Caroline puts out her cigarette." This is the end of the musical before the epilogue. That is symbolic for her death.
The epilogue, sung by Emmie, functions as a eulogy and elegy in this show. Her mother has died. As Caroline walks off the stage the stage directions say she "gives her daughter the stage" passing life and the matriarchal position to her. She sings because she now understands her mother, what her mother went through. SHe forgives her mother. She sings that (I think) even though her mother is dead, "still her strong blood flow...down to (HER CHILDREN) larry, and emmie and jackie and joe the children of caroline thibodeaux" This elegiacal piece is a testament to what her mother was and that change must come.
Caroline lived in a world of change. Caroline couldn't deal with change, and does not change. She escapes from change. This doesn't mean she hasn't learnt her lessons.
I believe the piece is a concrete piece, but I believe that it escapes into the surreal and abstract at many points, through symbols. Though everything can be looked at many ways, which is the artistic genius of Tony Kushner, I believe there is more than enough evidence to take this one of many stances.
"Yesterday is done. See the pretty countryside. Merrily we roll along, roll along- catching at dreams."- Merrily we roll along
"The living was the prize, the ending's not the story."- Elegies, a song cycle