What is the significance of Mrs. Joe's death?

I think that the death of Mrs. Joe reinforces what the reader already knows about Pip: He has chosen a lifestyle which alienates himself from the people he loves, and even alienates him from his true self. Although she was stern with him, there was a truth to their relationship. It was a sort of truth that Pip finds elusive in his other chosen life. Mrs. Joe represents a very real and honest part of his life that is lost forever.