What does the ending of the story suggest about the woman behind the wallpaper?

The ending of the short story, "The Yellow Wallpaper," suggests that the woman has, in her mind, become the woman in the wallpaper.  When she cannot fully remove the wallpaper from the wall and set her free, she becomes her and is thereby set free herself.

The narrator sees herself in an identical position as the woman in the wallpaper, anyway.  They are both trapped and imprisoned with no way of escape.  The narrator, throughout the story, projects her situation onto the wallpaper print, and becomes obsessed with setting the woman she perceives in the wallpaper free. 

When she cannot, she becomes her.  In her words:

I wonder if they [women outside of her room] all came out of that wallpaper as I did?

and

I suppose I shall have to get back behind the pattern when it comes night, and that is hard!

Having begun the narration with what we today call post-partum depression, the woman closes her story completely identifying herself with the woman in the wallpaper.