The focus of the prophecy shifts from Assyria to Israel.
10:20 In some future day, the remnant (cf. 6:13; 7:3) who escaped annihilation by the Assyrians would no longer trust in man for deliverance, as Ahaz and Judah did before the Assyrian takeover. They would learn this most important lesson and truly trust in Yahweh, the holy one of Israel. Thus Israel would be the really wise and strong nation, not Assyria (cf. v. 13). Israel, as well as Assyria (v. 19), would have a remnant left over after the Lord's destruction of both nations.
10:21 A remnant would return (Shearjashub, 7:3) to the genuinely mighty God. It would be a remnant of the whole house of Jacob, all the Israelites. The reference to the mighty God (cf. 9:5) along with the sincere change of attitude in Israel, one that has not yet taken place, points to a time of fulfillment in Messiah's reign. "That day"(v. 20), as elsewhere, is a millennial reference.
10:22-23 God had promised Abraham that his descendants would be as numerous as the sand of the sea (Gen. 22:17; 32:12). This did not mean, as the Israelites in Isaiah's day apparently concluded, that they would always be a large people. No, God would so thoroughly destroy them because of their sin that only a small number would survive (cf. Rom. 9:27-28). The sovereign Yahweh of armies would destroy them throughout the whole Promised Land, not just in the Northern Kingdom.
10:24-27 The Lord used reminders of two previous deliverances to encourage the residents of Jerusalem to believe that they would survive the attack of a stronger and larger foe. He had delivered their forefathers from Egypt and the Midianites, and He had destroyed the Egyptians and the Midianites (Judg. 7:25).131The Assyrian oppression would not last long (cf. 9:4), and God would then discipline the disciplinarian of His people. God's blessing on His people would be responsible for the breaking of the yoke of bondage on them.