Nephi’s transition out of the text-based pesher into a narrative prophecy picks up the most important theme of the pesher, the appearance of the Book of Mormon. Once restated, the appearance of the Book of Mormon has its value asserted (a logical continuation of the reason for its appearance) and then Nephi specifically mentions both the gentiles and the “remnant of the house of Israel.”
Nephi’s casting of the Jews as specifically the “remnant” has two purposes. First, in the context of Isaiah’s usage (appropriate because of the extensive reworking of Isaiah just completed) the “remnant” refers to an “end of time” description of the Jews. Secondly, the “remnant” at the end of time will be the righteous remnant - the one that will live with their Messiah in their midst. Nephi’s use of this term therefore continues the emphasis on the last days, but also adds another wrinkle.
Because the coming of the Book of Mormon is of great worth, that worth will bring the apostate Gentiles to their Lord, and will also be the instrument of the determination of the righteous remnant. The acceptance of the Book of Mormon and its message of Jesus Christ, the triumphant Messiah, will be the key to creating the righteous remnant from the Jews who are similarly apostate from their God, just as the Gentiles are.