This part of the prophecy specifies that the Nephite people as a political unit, not the genetic Nephites, will be destroyed. Not every person who was a Nephite will die, but the Nephite nation will be gone. Those who are left “shall be numbered among the Lamanites.” The process of switching sides rapidly associates former Nephites with current Lamanites, exactly the process employed by the Zoramites in Antionum (Alma 43:4).