Although most of the book simply observes the present moment and what's happening, the last couple of paragraphs delve into how Anna sees the future, and what their lives will be like now that Sarah has opted to stay:
When there are storms, Papa will stretch a rope from the door to the barn so we will not be lost when we feed the sheep and the cows and Jack and Old Bess. And Sarah's chickens, if they aren't living in the house. There will be Sarah's sea, blue and gray and green, hanging on the wall. And songs, old ones and new. And Seal with yellow eyes. And there will be Sarah, plain and tall. (9.62)
Anna's willingness to finally look forward and think about how awesome the future will be is a big deal because throughout the book, she manages her expectations and refuses to get tooexcited about Sarah. Remember that she's already lost one mother—it makes sense that she's constantly afraid Sarah will leave and disappoint them all. By the end, though, Anna trusts her new family configuration, and is completely happy that Sarah will stay.