What was foreshadowed by Madame Schacter's nightmare?

Madame Schächter's nightmare foreshadows the arrival of the Jews in Birkenau where the bodies of the prisoners are being burned.
Elie, his father, and the other Jewish people from the ghetto are made to ride in the cattle car of a train that departs from Hungary. They mistakenly believe that they are going somewhere else in this country to work in a brick factory. On this train is Madame Schächter, who has suffered the trauma of having been separated from her husband and two older sons who were mistakenly deported with the first transport. Now, with only her small son accompanying her, Madame Schächter is a broken woman. As the eighty people who are crammed into the cattle car move in the dark, Madame Schächter suddenly cries out, "Fire! I see a fire! I see a fire!" Some of the men try to look out into the night, but they see nothing.
Despite efforts to quiet the poor woman—some even strike her—Madame Schächter repeats her cry. A few men tie and gag her because she has greatly disturbed and frightened many of the passengers. Finally, when the train stops at Auschwitz, the people hear that it is a good work camp because families are not separated, and only the younger Jews work in the factories. Some of the people even give thanks to God. The occupants then try to rest and some doze until suddenly Madame Schächter cries out in the dark, "Fire! Look at the flames! Over there!" Again, the others try to quiet her, and one man asks a German officer that she be moved to a hospital; the officer replies that she will soon be taken off the train. 
Around eleven o'clock at night the train begins to roll slowly. Suddenly, there is a scream, and Madame Schächter calls out:

"Jews, look! Look at the fire! Look at the flames!" 

This time the others do see flames jumping from a tall chimney into a black sky. There is the stench of burning flesh in the air. They have arrived in Birkenau.