Nephi begins a new chapter after closing the previous chapter when the quoted text from Isaiah ended. His theme shifts from the coming forth of the Book of Mormon to the effect of the words of the book.
Nephi declares that the words of the book will be of great worth to all the children of men, but he singles out his own seed. Nephi sees that much of the purpose of the Book of Mormon is to bring the gospel to his own seed. At this point, he likely includes all of his father’s seed so that this promise extends to descendants of the Nephites and the Lamanites. He has already seen, in a vision, that the descendants of the Nephites will be destroyed, but yet declares that the Book of Mormon will be of benefit to his seed, even though it comes long after that prophesied destruction of the Nephites.