The story tells...
To contemplate how the short story "Desiree's Baby" by Kate Chopin might continue, it is important to consider the intention of the author in writing it and also to understand the main characters and how they might react to the events at the end of the story.
The story tells of Monsieur and Madame Valmonde finding an orphan toddler at the gate of their plantation and adopting her. She grows up to be a lovely young woman and Armand Aubigny, another rich plantation owner, rides by and falls in love with her. He marries her and takes her to his plantation, and they have a child.
Although Armand's plantation is a dismal place, devoid of laughter, Desiree is content with her husband and her child. Madame Valmonde is the first to notice that the baby is dark-skinned. Later, Armand notices, and eventually Desiree finds out. Armand accuses Desiree of not being white and asks her to go. In despair, she carries the baby with her and walks off into the bayou. At the end of the story, though, readers learn that Armand already knew that he had black ancestry, and the baby is most likely dark skinned because of him. However, he burns the evidence so that no one will find out.
Chopin obviously had the intention of exposing the terrible attitude of racism in this story.
To speculate how this story might continue is an interesting intellectual exercise. It could go in several directions, and we'll explore some of them. First of all, though, let's fill in the background a little better. The story is set in Louisiana before the Civil War. However, the specific era is not made clear. It mentions that possible Texans left the toddler Desiree at the plantation, and Americans did not begin to settle Texas until the nineteenth century. American Texans formed a republic in 1836, and Texas became part of the United States in 1845. All this is just to establish historical background.
Chopin writes that Desiree and her baby disappeared into the bayou. Most readers probably presume that they died there. However, what if her motherly instincts took over and she rescued herself and the baby? She might have made her way back to the estate of her adoptive parents. However, she might not have wanted to remain too close to Armand. In the mid-nineteenth century, the anti-slavery movement was strong in the northern states. Desiree might have felt that her son would have a better chance for a good life there, and as a result she might have moved to somewhere like New England. Possibly her parents might have even come with her. There her son would have grown up and possibly even enlisted in the Union Army to fight against the Confederates.
Meanwhile, Armand would have been wracked with guilt. As a result, he might have treated his slaves even more harshly. When the Civil War broke out, if he wasn't too old by that time, he might have wanted to prove his Southern manhood and enlisted in the Confederate army.
If we want to be truly melodramatic, we can envision Desiree's son and Armand, his father, fighting against one another in a famous battle of the Civil War.