Yes, but Paul has already said they were broken off through unbelief. It was Paul's hope that through salvation given even unto the Gentiles, SOME of those of his flesh might be saved. Any one of those of his flesh in unbelief who did not remain in unbelief, would be grafted back in again, and through those no longer in unbelief and the Gentiles of faith with them, it would mean the reconciliation of the world through faithful saints of all nations. Paul warns Gentiles to remain in faith, for if they too show themselves in unbelief, just as the natural branches found to be in unbelief were cut off, so too Gentiles shown to be in unbelief shall be cut off also.
Romans 11:13-14 (KJV) For I speak to you Gentiles, inasmuch as I am the apostle of the Gentiles, I magnify mine office: If by any means I may provoke to emulation them which are my flesh, and might save some of them.
Blindness in part happened to those in unbelief UNTIL the fulness of the Gentiles come in. It is in this way, that ALL ISRAEL shall be saved, not an ethnic people but all people of faith. Saved by the Deliverer who comes out of Sion to turn away ungodliness from Jacob. For the Covenant is unto THEM, when the Deliverer shall take away THEIR sins. Paul's kinsmen according to the flesh in unbelief concerning the Gospel are enemies for the sake of Gentiles of faith who shall now be grafted in with Israel of faith, not Israel in unbelief. Why? Because as touching election, Jews of faith and Gentiles of faith are beloved for the fathers' sake. For the Covenant according to election of grace is through Abraham, Isaac, and Jacob the beloved of God.
Romans 11:25-28 (KJV) For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in. And so all Israel shall be saved: as it is written, There shall come out of Sion the Deliverer, and shall turn away ungodliness from Jacob: For this is my covenant unto them, when I shall take away their sins. As concerning the gospel, they are enemies for your sakes: but as touching the election, they are beloved for the fathers' sakes.
That's why Paul has earlier written in Romans 9 that not all who are of Israel are Israel of faith, according to election of grace. Where is writes that though the number of Israel be as the sand of the seashore "only the remnant shall be saved." Because only true Israel of faith, that is both Jew of faith and Gentile of faith are "the Israel of God" (Gal 6:16). Not according to circumcision or uncircumcision but according to the like faith of the fathers' according to election.
But your argument says unbelief was removed because of the Cross. The reality is unbelief was introduced because of the Gospel. They were cut off and enemies because of the Gospel.
The Cross cut them off, and they will be cut off until the Second Coming. You say they were cut off, and brought back at the first coming. The blindness in part was because of the Cross, and yes they can overcome that blindness. But the Second Coming, not the first coming removes that blindness. Most Amil deny that Israel will be restored at the Second Coming. Not in Satan's little season, but a thousand years prior to Satan's little season.
The restoration is about Israel at the time of the Second Coming. Not retroactive from thousands of years ago. Amil want to argue restoration is the here and now, only on the basis there is no future millennium. It is reformed theology that claims the 70th week was finished in the first century.
The 70th week is over at the 7th Trumpet. The 7th Trumpet is the start of the thousand years in Revelation 20. The time up is the time of Daniel, those 70 weeks, not time itself. Daniel did not cover all of earthly time. Only the last 3500 years.
"But in the days of the voice of the seventh angel, when he shall begin to sound, the mystery of God should be finished, as he hath declared to his servants the prophets."
Time was called up, but surrounding the mystery of God. Most call that the Gospel. So I agree the Gospel ends at the 7th Trumpet. So there is no need of the Gospel, while Jesus is physically on earth as the King over all nations. The iron rod rule will prevent disobedience and sin and death entering the world. It is sin and death that makes the Gospel necessary.
"Seventy weeks are determined upon thy people and upon thy holy city, to finish the transgression, and to make an end of sins, and to make reconciliation for iniquity, and to bring in everlasting righteousness, and to seal up the vision and prophecy, and to anoint the most Holy."
No Gospel is necessary after these promises are implemented. As long as there is a Gospel preached, the 70 weeks are still not complete. The Cross was half of the equation as Messiah. The second part is being Prince over the entire earth. That is when blindness in part is removed, and a remnant, some from those alive at the Second Coming, a third are redeemed and live out the fulfillment of Daniel 9:24 for a thousand years.
I am not sure how you can reconcile that Israel received in full the 70th week, and was placed under blindness and made enemies of the Gospel at the same time. The 70th week was not the coming of the Gospel. The Gospel was the inclusion of the Gentiles for an entire 2,000 years before the full effect of the 70th week. Those left out would be destroyed. Yet even after the Second Coming, Jesus is still offering salvation and redemption out of those still in bondage to Adam's dead corruptible flesh. The restoration is on God's terms, not that Israel nor the Gentiles choose God.
God can still choose according to election, those who are enemies of the Gospel. Election is not at work during the time of the Gospel. Those in blindness are not auto redeemed. Israel was cut off. That is the whole point of no difference between Israel and Gentile. All have to come by faith of the second birth to be grafted in. Yet many just want to see this as a continuation of Israel and that the 70th week was over. That is not Israel restored, the Second Coming is Israel restored. Daniel even pointed out, Messiah would be cut off, but not for Himself. The cut off part was the Gospel going out to all on earth, both Israel and the Gentiles. The Prince to come part is the Second Coming, and the point of the sounding of the 7th Trumpet.