IP, regarding your post, in the Spoiler below...
There is often a thing that differs between what is written in Scripture about one thing or another, and what it's reader might understand it is actually referring to.
And the Scripture is a witness of this very reality being the likely case.
John 11:11 These things said he: and after that he saith unto them, Our friend Lazarus sleepeth; but I go, that I may awake him out of sleep. 11:12 Then said his disciples, Lord, if he sleep, he shall do well. 11:13 Howbeit Jesus spake of his death: but they thought that he had spoken of taking of rest in sleep. 11:14 Then said Jesus unto them plainly, Lazarus is dead.
They appear to have BELIEVED what He'd said.
Actually, they had believed what THEY had read INTO what He'd said.
They had believed THEIR OWN understanding.
Proverbs 3:5 Trust in the LORD with all thine heart; and lean not unto thine own understanding.
Which is where one might do well to ask questions seeking clarification as to what might have actually been the intended sense or meaning.
The same is the case with the assertions and or writings of one individual or another.
I doubt any Dispy holds that "all Israel shall be saved" is actually a reference to every literal, physical Israelite who has ever lived.
Rather, the Dispy's understanding is that that refers to all literal, physical Israel that BELIEVED (OT) or that BELIEVES (NT and post the NT era).
John 5:28 Marvel not at this: for the hour is coming, in the which all that are in the graves shall hear his voice, 5:29 And shall come forth; they that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation.
The Lord's words later - through the Apostle Paul - is that same distinction between said two literal, physical Israelites...
Romans 10:1 Brethren, my heart's desire and prayer to God for Israel is, that they might be saved.
At one point he quotes the Psalmist on the witness of the stars all Israel has always had...
Romans 10:18 But I say, Have they not heard? Yes verily, their sound went into all the earth, and their words unto the ends of the world.
And the witness in the Law and the Prophets about those within physical, literal Israel who's Belief in Messiah in His day, had been meant to provoke to jealousy, those in Unbelief within their Nation...
Romans 10:19 But I say, Did not Israel know? First Moses saith, I will provoke you to jealousy by them that are no people, and by a foolish nation I will anger you. 10:20 But Esaias is very bold, and saith, I was found of them that sought me not; I was made manifest unto them that asked not after me.
That right there refers to Israelites like these here...
John 1:45 Philip findeth Nathanael, and saith unto him, We have found him, of whom Moses in the law, and the prophets, did write, Jesus of Nazareth, the son of Joseph.
Thus, this distinction between THEIR BELIEVING Remnant, and "the rest..."
Romans 10:21 But to Israel he saith, All day long I have stretched forth my hands unto a disobedient and gainsaying people.
As with the distinction between the two literal, physical Israelites within that Nation's past, so in Paul's day...
Romans 11:4 But what saith the answer of God unto him? I have reserved to myself seven thousand men, who have not bowed the knee to the image of Baal.
Romans 11:5 Even so then at this present time also there is a remnant according to the election of grace. 11:6 And if by grace, then is it no more of works: otherwise grace is no more grace. But if it be of works, then is it no more grace: otherwise work is no more work. 11:7 What then? Israel hath not obtained that which he seeketh for; but the election hath obtained it, and the rest were blinded.
Continually, he makes this distinction between both literal, physical Israels.
Nehemia 8:8,12
Acts 17:11,12