Lehi reiterates the mission of Joseph Smith, though he allows himself the literary license to lump the differing branches of the house of Joseph into a single entity, which is the explanation for the "and there shall rise up one mighty among them..." where the antecedent is clearly the posterity of Joseph, son of Lehi.
2 Nephi 3:25
25 And now, blessed art thou, Joseph. Behold, thou art little; wherefore hearken unto the words of thy brother, Nephi, and it shall be done unto thee even according to the words which I have spoken. Remember the words of thy dying father. Amen.