I think I posted some of this already...
Isa 19:23-25
23 In that day shall there be a highway out of Egypt to Assyria, and the Assyrian shall come into Egypt, and the Egyptian into Assyria, and the Egyptians shall serve with the Assyrians.
24 In that day shall Israel be the third with Egypt and with Assyria, even a blessing in the midst of the land:
25 Whom the LORD of hosts shall bless, saying, "Blessed be Egypt My people, and Assyria the work of My hands, and Israel Mine inheritance.
KJV
Not only will Israel then be the kingdom Lord Jesus spoke of, but Israel will only be one-third of it. Assyria and Egypt will each be the other two-thirds.
Isa 56:6-8
6 Also the sons of the stranger, that join themselves to the LORD, to serve Him, and to love the name of the LORD, to be His servants, every one that keepeth the sabbath from polluting it, and taketh hold of My covenant;
7 Even them will I bring to My holy mountain, and make them joyful in My house of prayer: their burnt offerings and their sacrifices shall be accepted upon Mine altar; for Mine house shall be called an house of prayer for all people.
8 The Lord GOD Which gathereth the outcasts of Israel saith, "Yet will I gather others to him, beside those that are gathered unto him."
KJV
One may deem the first part of the above as OT history, but that verse in red is still future, and is about the gathering of believing Gentiles to the holy land also with Israel.
Isa 54:2-3
2 Enlarge the place of thy tent, and let them stretch forth the curtains of thine habitations: spare not, lengthen thy cords, and strengthen thy stakes;
3 For thou shalt break forth on the right hand and on the left; and thy seed shall inherit the Gentiles, and make the desolate cities to be inhabited.
KJV
You might struggle with the above parable in the first verse, but its idea is about those who remain spiritually chaste waiting for Christ's coming. In that sense, their wombs remaining barren represent staying a "chaste virgin" in the spiritual sense, for Christ (2 Corinthians 11:2). So that points that 'blessed are the barren' metaphor is about Christ's Church particularly. However, it is pointing to the holy land and the restoration of Israel at the same time.
Acts 15:14-17
14 Simeon hath declared how God at the first did visit the Gentiles, to take out of them a people for His name.
15 And to this agree the words of the prophets; as it is written,
16 "After this I will return, and will build again the tabernacle of David, which is fallen down; and I will build again the ruins thereof, and I will set it up:
17 That the residue of men might seek after the Lord, and all the Gentiles, upon whom My name is called, saith the Lord, Who doeth all these things."
KJV
What name would that be? It is the name Christian, those who believe on Christ Jesus, His Church.
Eph 2:11-13
11 Wherefore remember, that ye being in time past Gentiles in the flesh, who are called Uncircumcision by that which is called the Circumcision in the flesh made by hands;
12 That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world:
13 But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ.
KJV
By that, Apostle Paul showed that the Israel under Christ Jesus is a commonwealth of peoples, and so it is with His Church today, made up of peoples from many nations, for like Paul said there is no difference between Jew and Gentile. This doesn't mean those born of Israel stop being Israelites; it means the believing Gentiles are graffed in with believing Israel, and have become joined with them. And thus like God showed in Isaiah 54, an Old Testament Book that is specifically about His Salvation, the tent of Israel in the holy land will be enlarged to include the believing Gentiles.