2 Nephi - Chapter 21

 4 But with righteousness shall he judge the poor, and reprove with equity for the meek of the earth; and he shall smite the earth with the rod of his mouth, and with the breath of his lips shall he slay the wicked.

It is easy to assume that in this verse slay means to literally kill the wicked.  And while this is obviously true in many cases, I wonder if me might consider another possibility.  Later in The Book of Mormon we will discover that the Lamanites destroyed the Gadianton robbers from among them.  Read how this was done:

 Helaman 6:37 And it came to pass that the Laminates did hunt the band of robbers of Gadianton; and they did preach the word of God among the more wicked part of them, insomuch that this band of robbers was utterly destroyed from among the Laminates. 

Is it not entirely possible that, hearing His voice and His teachings will have the same effect upon the peoples of the earth that the preaching of the Lamanites had upon the Robbers of Gadianton?  Perhaps the slaying and destruction refers to the old man of sin and not necessarily the destruction of the body, at least in many cases.  Could it not also be that the cleansing of the earth by fire, at His coming, could be as by fire and the Holy Ghost?  Certainly it can be if we so choose.

At any rate, the Millennial reign of the Master will we a wonderful time.  A time only imagined in all the history of the earth.  Telestial living hasn't been all that bad in the aggregate.  Terrestrial living will be a wonderful new opportunity and step toward eventual Celestial living.  Oh, that it might come soon for the sake of the children.