Not ALL Old Testament prophecies were fulfilled with the coming of the Christ in the first century of our age. For instance, many New Testament prophecies of the end of this present universe are quotes from the Old Testament. For instance Heb 1:10-12, and 1Cor 15:54-55, and much more. So it is with many things concerning the Jews. Their conversion will be in a time of severe stress on both Christians (first), and then the Jews. Of the Jews it says,

“11 He will pass through the sea of affliction, …
12 I will strengthen them in Yahweh;
And they will walk up and down in his name,” says Yahweh.”
Zech 10:11

Jesus will NOT be on earth again.

Instead we will meet Him in the air, 1Thes 4:16-17.

“If therefore they tell you, ‘Behold, he is in the wilderness,’ don’t go out; ‘Behold, he is in the inner chambers,’ don’t believe it.”
Mtt 24:26

You may or may not believe that, but that IS what Jesus says. In fact, Jeremiah tells us that no descendant of Jeconiah/Coniah will ever rule “in Judah.”

“Thus says Yahweh, Write you this man childless, a man who shall not prosper in his days; for no more shall a man of his seed prosper, sitting on the throne of David, and ruling in Judah.”
Jer 22:30

However, Jesus is a descendant of Jeconiah/Coniah, Mtt 1:11-12. Now that fits 1Thes 4:16-17, but not premillennialism.

Jesus has NOW “ALL authority … in heaven
and on earth,” Mtt 28.18

Jesus NOW rules over the kings of the earth, Rev 1:5, from heaven!

In prophecy there are often subtle shifts in subject.

Prophecy commonly ties the immediate things talked about, with the ultimate things which will happen. A prophecy of Israel’s sins of old will often jump from ancient Israel’s punishments by Assyria and Babylon, to the ultimate punishments at the end of this universe. Also many prophecies of the good that will come from the church or the Jews being faithful to God, jump from temporal benefits in this world to eternal benefits in “the world to come” (Heb 2:5).

An example is Isaiah 65.

God speaks of the new heavens and new earth, Isa 65:17-19. There will be no weeping or crying, Isa 65:19. That is only in heaven itself, Rev 21:4. But a child will die at age 100, and the sinner dying at age 100 will be considered cursed, Isa 65:20. But that does not fit heaven -or- this world so far. A shift of subject matter.

The faithful Jews will cause an astonishing extension of human life on earth. This will be the golden age of the church in this world, but it will not quite be heaven. The Jews will still just be men, converting to Jesus. Jew and gentile will truly be one in Christ, Eph 2:18-22. Even so, “evil men and impostors will grow worse and worse,” 2Tim 3:13. Mystery Babylon the Great (Revelation 14 to 18), and the Mystery of Lawlessness (2Thessalonians 2) will still be biding their time.

Scriptures are from the World English Bible WEB, a copyright free revision
of the original ASV American Standard Version 1901.