The Nephites have an apparent advantage over their counterparts in the Old World. This explicit revelation of the person and mission of the Messiah has prepared them with the correct understanding of the nature of the law of Moses. Where the Jews of the Old World were convinced that their status as the chosen of God came through obedience to the laws, the New World Nephites understood that all of the law of Moses was to prepare them for the fulfillment of that law through Christ.
Nephi certainly sees and predicts the time when the law is "done away." Once again, this is an echo of Pauline theology, but also an accurate picture of the way the Christian doctrine has influenced the development of a Christian religion. For Nephi, the mission of the Messiah fulfills the law in such a way that it is supplanted. Nevertheless, he understands that there is value in the law, and for that reason, he and his posterity will keep the law until it is fulfilled.
For however great their understanding of and hope in Jesus Christ, they also clearly understood that the law was to last until the time of its fulfillment, and that their knowledge of the gospel of Christ was not sufficient to fulfill the law. For Nephi, the fulfillment of the law occurs in the person and atonement of Jesus Christ, not in his doctrine.