The common evangelical view is that a mass of Jews, the bulk of living Jews close to the time or at the time of Christ's final appearance will turn to God in faith in Jesus Christ. This they think is the fulfillment of Romans 11:6, "And so all Israel will be saved." Perhaps this is true but we need to recognize the gravity of the loss if this view is correct. Besides, I don't think such a view would accomplish Paul's aim. First, there's the gravity of the loss if this view is correct.
As Paul presents it, God hardens the Jewish unbelievers and they reject the Christ but this is to bring salvation to the world (11:8-11,15). He says the hardening would last "until the fullness of the Gentiles has come in" (11:25). Numerous people take that to mean "until the last Gentile is saved," or as some versions render it, "until the full number" of Gentiles has arrived. Since Gentiles are still being saved these people think that 11:25 hasn't yet been fulfilled. They think it will be fulfilled close to or at the final appearance of Christ. When the last Gentile is saved, God will end the hardening that blinds Israel and they will turn to Christ en masse.
And what of the Jews between the 1st century and the 21st? Imagine a Jew asking Paul how God proposes to maintain his faithfulness to all of Abraham's descendants through Jacob. Imagine Paul saying something like, "God will continue to harden Israel for two thousand years and then, close to the time when the Messiah makes his final appearance, God will end his hardening work and save the bulk of that generation then alive." What do you suppose that Jew would say?
Remember that "all Israel will be saved" is Paul's way of denying that God is faithless! And would his saving the bulk of a single generation of Jews in (say) the 21st century show his faithfulness to fifty generations of Jews that he hardened? Two thousand years of hardening is to be offset by his saving the bulk (or even all) of a single 21st century generation of Jews?
As for me, it seems better to hold that God's judicial hardening of unbelieving Jews lasted until the door was opened for Gentile blessing (see 11:30-32). That was occasioned by the death (and glorification) of the Messiah when God made Gentiles full of the spiritual wealth that he had always promised to Israel. Once the door had been thrown wide open the gospel was for all (11:32).