Ah. No sweat. God will keep His promise to His Chosen despite your incorrect opinions.
*yawn*
Romans 11
11 I say then, Have they stumbled that they should fall? God forbid: but rather through their fall salvation is come unto the Gentiles, for to provoke them to jealousy.
12 Now if the fall of them be the riches of the world, and the diminishing of them the riches of the Gentiles; how much more their fulness?
Their fullness consists of
those who believe in Jesus.
Romans 11
25 For I do not want you to be ignorant of this mystery, brothers, lest you should be wise within yourselves; that blindness in part has happened to Israel,
until the fullness of the nations has come in.
26 And so all Israel shall be saved; as it is written,
"There shall come out of Zion the Deliverer, and He will turn away ungodliness from Jacob.
27 For this is My covenant with them,
when I have taken away their sins."
That covenant came 2,000 years ago when Jesus took away their sins.
28 Indeed as regards the gospel, they (Jews who do not believe) are enemies for your sakes. But as regards the election, they are beloved
for the fathers' sakes.
So they can be grafted in again IF they repent of their unbelief while the fullness of the Gentiles is coming in:
23 And those also,
if they do not continue in unbelief, will be grafted in. For God is able to graft them in again.
Many thousands of Jews have been grafted in again over the last 2,000 years, and it continues today, because through the mercy shown to the Gentiles (the house of Israel who once were not a people and had not received mercy, but are now called children of the living God), God will also show mercy to those of the house of Judah (or the Jews)
who repent and believe in Jesus, so all Israel (those who believe in Jesus, both Jew and Gentile) will be saved:
30 For as you also then disbelieved God, but now have been shown mercy
through their disbelief,
31 even so these also have not believed now, so that
through your mercy they may also obtain mercy.
32 For God has shut up all (Jews and Gentiles, the house of Israel and the house of Judah) in unbelief, so that He might show mercy to all.
He shows mercy to all who repent and place their faith in Jesus, whether Jew or Gentile.
What Paul is talking about is not future tense, as you imagine. The covenant He made with them when He took away their sins is the same covenant He made with all who believe in Him.
What Paul is talking about is the fact that both the Jew who at first rejected Jesus will receive mercy IF he repents, just as we non-Jews who believe have received mercy, IF and when he or she repents and turns to faith in Jesus.
Hardness in part has happened to Israel, because those for whom it was meant (the Jew first) are hardened, and have been since Christ came. But only a remnant of Israel will be saved, i.e the Jews and the Gentiles who believe in Jesus. Isaiah said only a remnant will be saved. A remnant of the Jews and a remnant of the Gentiles. Yet the whole house of Israel has been saved by Christ already, i.e the remnant.
Your imagination runs wild with this.