I actually agree with all of this up to the last line.. This hardening was specifically for ISRAEL, who was already in rebellion... and God was blinding them in that rebellion to accomplish all these things you mentioned.
But has Israel (those stumbling, those being hardened, those being sent a spirit of stupor, those being cut off), stumbled beyond recovery, been hardened beyond hope of salvation, been blinded beyond hope of ever seeing, been cut off without hope of being grafted back in again? I'll allow Paul to answer each of those questions in his own words:
Did they stumble so as to fall beyond recovery? Not at all! Rather, because of their transgression, salvation has come to the Gentiles to make Israel envious. 12 But if their transgression means riches for the world, and their loss means riches for the Gentiles, how much greater riches will their fullness bring! 13 I am talking to you Gentiles. Inasmuch as I am the apostle to the Gentiles, I make much of my ministry 14 in the hope that I may somehow arouse my own people to envy and save some of them. 15 For if their rejection is the reconciliation of the world, what will their acceptance be but life from the dead? 16 If the part of the dough offered as firstfruits is holy, then the whole batch is holy; if the root is holy, so are the branches. 17 If some of the branches have been broken off, and you, though a wild olive shoot, have been grafted in among the others and now share in the nourishing sap from the olive root, 18 do not boast over those branches. If you do, consider this: You do not support the root, but the root supports you. 19 You will say then, "Branches were broken off so that I could be grafted in." 20 Granted. But they were broken off because of unbelief, and you stand by faith. Do not be arrogant, but be afraid. 21 For if God did not spare the natural branches, he will not spare you either. 22 Consider therefore the kindness and sternness of God: sternness to those who fell, but kindness to you, provided that you continue in his kindness. Otherwise, you also will be cut off. 23 And if they do not persist in unbelief, they will be grafted in, for God is able to graft them in again.
That doesn't sound "irreversible" to me.