If you look further on in the prophecy we see it points to the time of Christ, the gospel being proclaimed and the bringing in of the tribes mentioned in James letter (which John in the book of revelation name symbolically the 144.000):
Jer 31:15 Thus saith the LORD; A voice was heard in Ramah, lamentation, and bitter weeping; Rahel weeping for her children refused to be comforted for her children, because they were not.
James 1:1 James, a servant of God and of the Lord Jesus Christ, to the twelve tribes which are scattered abroad, greeting.
Paul stated the salvation of the remnant would be a short work:
Rom 9:27 Esaias also crieth concerning Israel, Though the number of the children of Israel be as the sand of the sea, a remnant shall be saved:
Rom 9:28 For he will finish the work, and cut it short in righteousness: because a short work will the Lord make upon the earth.