In 1 Nephi, Nephi had developed the way in which the prophecy was fulfilled that he would be a teacher over his brothers. As he prepares for the New World story, it will be a story of Nephi becoming a ruler. However, there is another transition that had begun, and Nephi wanted to bring it to a close. Nephi had subtly shown his ascendance in the leadership of the family, assuming more of the prophetic role than his father. That process is completed in the New World, and to show the final form of that transition, Nephi writes his father’s blessings to his sons. In these blessings, the future form of the division between Lamanites and Nephites will be prophetically laid out, and then Lehi will die. Nephi will become the new religious leader, as well as found the city that will serve as the base for the beginning of the people called Nephites.
As Lehi begins, he addresses Laman and Lemuel. The theme will be their rebelliousness, and Lehi begins with his prophetic understanding of the destruction of Jerusalem. The desire to return to Jerusalem had been a constant subtheme in the descriptions of Laman and Lemuel. Perhaps they still harbored some desire to return. Lehi informs them that it is impossible. There is nothing to which to return. Not only is there nothing to return to, but that destruction justifies the family’s exodus in which they have perhaps unwillingly participated.
The destruction of Jerusalem also provides a point of prophetic fulfillment. The Old World connection no longer exists. From this point on, Nephi is telling the story of the creation of a new people rather than the travails of a couple of families.
There isn’t a clear closing point to Lehi’s recounting of Laman and Lemuel’s rebellions, but at this point Lehi will no longer address Laman and Lemuel directly; he will address all of his children. It is tempting to see this address to Laman and Lemuel as part of Nephi’s literary device to move from his address to his brothers, and then to his father’s blessings to the family, which do more appropriately begin with the whole family rather than just focusing on Laman and Lemuel.