This is literally the ending of Mormon’s record. This is the beginning of his final chapter, even though we have two chapters covering his original structure. Thus when Mormon begins this chapter, he knows that he is ending his record. When this chapter ends at the end of our current chapter 7, we will have the text that Mormon intended to write to future generations. In a very real sense, we should consider our chapters 6 and 7 as the end of Mormon’s work.
It is interesting to note that this final chapter necessarily follows the destruction of his people, because that incident is included in the record. Thus Mormon not only survives the final battle, but survives long enough to finish his record. We cannot tell how long he lived, or how much of the record was written after that date. However, we do know for a fact that this record was written after that time.
The very fact that this is the final chapter, and it was written after the final battle, seems to suggest something that Mormon never tells us. It would appear that the Lord had promised him that he would live through the final battle. Even though there is no record of the promise, it is implied in the fact that Mormon does not write his conclusion to his work until after that battle. Going in to the battle he was preparing for a final destruction, and in his heart (and perhaps through revelation) he understood that this would be the last battle. With such a pessimistic outlook, why doesn’t he finish the work earlier? Why isn’t the last chapter written before the battle with the fatalistic admonition that he might not live to finish the work. Since we find nothing of that, we must assume that Mormon knew that he would survive so that the ending might be written. No one could have given him that confidence save the Lord himself.