Narrative: Having established a connection between his people’s destruction and convincing the Gentiles that Jesus is the Christ, Nephi now describes the future after his people’s destruction. Again, he alludes to Isaiah 29:5: “Moreover the multitude of thy strangers shall be like small dust, and the multitude of the terrible ones shall be as chaff that passeth away: yea, it shall be at an instant suddenly.”
Nephi ties Isaiah’s words to his new context—his people’s destruction. He has already noted that the end comes quickly after the Spirit withdraws (v. 11). He uses Isaiah to emphasize the speed of that destruction.
Nephi certainly understands that the Lamanites will survive the Nephites. Nephi may be acknowledging that the Lamanites have had some semblance of the gospel by describing them as having “dwindled in unbelief.” This “dwindling” implies a time of belief before the “dwindling” occurred. However, a second possibility is that Nephi understands that his people, though destroyed, may not be completely eradicated, and that some remnant of his people may survive in the New World during the Gentiles’ smiting. Nephi continues to talk about “his people,” rather than the “Lamanites,” which would be natural if he was talking about them as his people’s successors.