‘In that day will Israel be the third with Egypt, and with Assyria, a blessing in the midst of the earth, because Yahweh of hosts has blessed them, saying, “Blessed be Egypt my people, and Assyria the work of my hands, and Israel my inheritance.'
Finally this is all related to Israel. Here Israel represents the future Israel made up of the remnants of both Judah and Israel. And with Egypt and Assyria they will be all one together in the worship of Yahweh. All will be a blessing to the world. Egypt will be His people (compare Isaiah 10:24; Isaiah 43:6-7; Exodus 5:1; Hosea 1:10; Hosea 2:23; Jeremiah 11:4), Assyria the work of His hands (compare Isaiah 60:12; Isaiah 64:8; Psalms 119:73; Psalms 138:8), Israel His inheritance. These are descriptions which were once reserved for Israel but are now applied to all, for there is neither Jew nor Gentile. All have become one in Christ Jesus (Galatians 3:28). The mightiest nations of the world, together with the chosen nation, will be united to serve Yahweh. It is Isaiah's way of depicting God's universal triumph.
Note the advancement in the spiritual life depicted. First trembling and fear before God and His ministers (Isaiah 19:16-17), then a change of language, the sign of the acceptance of a new way of life and thought, followed by a commitment to Yahweh (Isaiah 19:18), then the outward declaration of their new belief and their open admission that they are God's, as represented by the altar and the pillar (Isaiah 19:19), then the deepening in the knowledge of God, and the offering of worship, praise and thanksgiving, together with specific commitments to His service (Isaiah 19:21), then the sense of oneness with all who serve God (Isaiah 19:21), and finally their becoming a blessing to the world (Isaiah 19:24-25).