To answer this type of question, look at the characters and the ending and decide how you would want the Gribleys to be living a year later. Do you want them to live the type of life that Sam did in the woods? Or, would you want Sam to decide to go back to the city, go to school and become something that would allow him to use his love of nature and the outdoors, such as a park ranger? Your own personal preferences come into play here. You just have to come up with a narrative that supports the ending of the story.
Actually, the author wrote two more books after the first book. The second book is called On the Far Side of the Mountain and is about Sam and his sister living in the woods. It deals with how different Sam and his sister are, in that she likes what the city can offer her. The third book of the trilogy is Frightful's Mountain, told from the falcon's point of view.