Who is Israel in the “all Israel” will be saved (Rom. 11:26)? There are three basic options:
1. Spiritual Israel: the Church and all (elected) Jews who believe in Jesus as Messiah.
2. Ethnic Jews: either those at the time of Paul or the final generation before the Parousia.
3. Twelve-tribe Israel: Israel, then, is larger than “Jews,” who are part of Judah and Benjamin.
This is not an extensive discussion, but the following points deserve consideration:

1. Rom 1–8 deals with “Jews” while 9–11 with “Israel.” Does Paul mean a distinction? Probably some kind of shift is in view.
2. Rom 9–11 banks its support from passages that deal with the tribal nature of Israel.
3. The OT expected the restoration of the Twelve Tribes (Isa 11:11-12, etc).
Does Paul mean with “all Israel” then that Gentile inclusion, Israelite jealousy, and Israelite hardening are designed to spread the gospel into all the world so that redemption extends into “all the tribes of Israel”?
Wright thinks “all Israel” refers to “all the elect, Jews and Gentiles alike,” and that redemption will occur during the course of present history, and it will occur by turning to the Messiah.
I consider his view, or the view I suggested tentatively — in conversation with a few friends, are the only real options: I do not think Paul is speaking of an eschatological return of Israel at the Parousia, though I’m more than aware that many think this. I’m not sure Wright takes the difference between “Jews” in Rom 1–8 and “Israel” in 9–11 enough into consideration, with the latter clearly concerned with “tribal” matters. If the latter suggestion has merit, Paul is saying that Israel’s hardening and Gentile inclusion will provoke Israel to jealousy and then ethnic Israel from all the tribes will be provoked to faith in the Messiah. No small plan on Paul’s part, that.
Nor am I persuaded that “Israel” in 11:26 (elect) can be differentiated from “Israel” in 11:25 (ethnic Israel).
What this suggestion asks is that theme of Israel’s jealousy accompany the hardening of Israel and Gentile inclusion. If it is, then the “all Israel will be saved” is Paul’s hope for his people: that Gentile faith will provoke them to jealousy.