The Hebrew particle rendered For is an emphatic marker here since it introduces a conclusion. It is better to say “Yes” (Bible en français courant) or “Indeed.” Many translations ignore the particle (so Good News Translation, New International Version, Revised English Bible, New American Bible).
Thus it shall be in the midst of the earth among the nations: These two lines point back to the destruction described in the previous verses and emphasize that it will happen. The phrases in the midst of the earth and among the nations are synonymous. A better English rendering for in the midst of the earth is “throughout the world” or “all over the world” (Good News Translation). Among the nations refers to all the nations.
As when an olive tree is beaten, as at the gleaning when the vintage is done: There are two similes here. For the simile as when an olive tree is beaten, see the comments at 17.6. As at the gleaning when the vintage is done refers to the time when gleaners go through a vineyard to pick any grapes that remain after it has been harvested. The vintage may be rendered “the grape harvest.” For comments on vineyard and the grapes that grow there, see 1.8. These similes compare the earth’s devastation to the few olives and grapes that remain after the harvest. Just as the olive trees and the vineyards are empty after the harvest, so the earth will be desolate after its destruction.
Translation examples for this verse are:
• Indeed, this is what will happen throughout the earth
among the people/nations.
It will be as desolate as when an olive tree is harvested of fruit,
or as when few grapes are left after the picking.
• Truly, this is what is going to happen
throughout the world among the nations.
It will be desolate like an olive tree stripped of its fruit at harvest time,
or like a vineyard after the grapes have been harvested.
Quoted with permission from Ogden, Graham S. and Sterk, Jan. A Handbook on Isaiah. (UBS Helps for Translators). New York: UBS, 2011. For this and other handbooks for translators see here .