‘Whereas you have been forsaken and hated,
So that no man passed through you,
I will make you an everlasting excellency,
A joy of many generations.
You will also suck the milk of the nations,
And you will suck the breast of kings,
And you will know that I, Yahweh, am your Saviour,
And your redeemer, the Mighty One of Jacob.'
This new Zion, once forsaken and hated and avoided by men, will be given everlasting excellency, it will be the joy of the people of many generations. The nations and kings will see that it is amply supplied with nourishment and with good things. There may also be the suggestion that its very inhabitants will be fed by nations and by kings for they will know that Yahweh is their Saviour and Redeemer, the Mighty One of Jacob.
This Jerusalem represents the centre where God is seen to be with His Servant, and includes the purified remnant who remain after God's judgments as described earlier in the book, the people who as a result of God's active grace have sought His face and found forgiveness and mercy (Isaiah 57:17-19). And as we have seen above and elsewhere they include among them people from many nations, ‘strangers'. It represents the faithful in Israel. It includes all who have responded to Yahweh. And it must include all who have been raised from the dust (Isaiah 26:19). It represents all those incorporated into the Israel of God from wherever they come (Galatians 6:16). Thus it portrays the called out and chosen people of God through many generations (Galatians 4:26; Galatians 4:31; Hebrews 12:22), both the old and New Testament churches. It is the multitude which no man can number (Revelation 7:9).
‘You will also suck the milk of the nations, and you will suck the breast of kings.' here is a clear example that Isaiah is not speaking literally. They would not get much milk from the breasts of kings! But the idea is of maternal care and provision which they will enjoy from nations and kings, including the cup of cold water in His name, as all become one with God and with His people. This may partly represent care from those who have conjoined with them in the new Israel, as the Gentiles flock to Christ. We may compare here ‘the collection' made by the people of God around the world for the Christians in Jerusalem and Judea (1 Corinthians 16:1; 1 Corinthians 2 Corinthians 8-9). Or it may represent the care of God's chosen ones by some of the outer world whose hearts He would move. God's people were not always to be persecuted, there would be times of refreshing and even acceptance by kings and their people.
Note that He is ‘the Mighty One of Jacob', which certainly expresses His great power, possibly in contrast with the weakness of His people (‘you worm Jacob' - Isaiah 41:14), or there may be the hint behind this title of the fact that they are Jacob His chosen, and not Esau the rejected (see Isaiah 63:1-6; compare Malachi 1:2-3).