John Calvin Commentary Isaiah 49:19

"For, as for thy waste and thy desolate places, and thy land that hath been destroyed, surely now shalt thou be too strait for the inhabitants, and they that swallowed thee up shall be far away." — Isaiah 49:19 (ASV)

For thy desolate places, he confirms by other words what we have already seen: that the change which he promised is in the hand of God, and that the Church, which was for a long time ruined and desolate, may soon have many inhabitants; so that the place may be too narrow to contain them all. He uses the metaphor of a ruined city, whose walls and houses are rebuilt, to which the citizens return in such vast numbers that its circumference must be enlarged, because its former extent cannot contain them all. Thus he means not only the return of the people from Babylon, but the restoration which was effected through Christ; that is, when the Church was spread far and wide, not only throughout Judea, but throughout the whole world.

And thy destroyers shall remove far away. He adds that a garrison will be provided if any enemies should harass her; indeed, that she will be secure against their attacks and harassment, because God will “drive them far away.” Not that the Church will ever enjoy perfect peace and be secured against all the attacks of enemies; yet God, bearing with the weakness of his people, defended them from wicked men, and restrained or warded off their attacks, so that at least the kingdom of Satan might not grow out of the ruins of the Church.