[continued from previous post]
[note Wm Kelly's Commentary per BibleHub... quoting below]
"But, this is not the only point of interest in this appendix to the prophecy. For the Lord has given us the positive proof. by the way in which verse 32 stands here, that "this generation" cannot mean a mere chronological space of thirty or even one hundred years, for it is brought in after the running out of Gentile times and the coming of the Son of man with power and glory, events still unfulfilled. Its force is moral; not exactly the nation of Israel but that Christ-rejecting race which then refused their Messiah as they do still. This will go on till all these solemn threats of judgment are accomplished. It is profitable to remark that here, not in doctrine or in practice only, but in these unfoldings of the future, the Lord pledges the impossibility of failing in His words. The Lord does not say that this generation "shall not pass away till the temple is destroyed or the city taken, but till all be fulfilled. Now, He had introduced the subsequent treading down of Jerusalem to the end of Israel's trials at His appearing, and He declares that this generation shall not pass away till then; as indeed it is only then grace will form a new generation, the generation to come. The more we hold fast the continuity of the stream of the prophecy, as distinguished from the crisis in Matthew and Mark, the greater will be seen to be the importance of this remark."
[and]
[quoting Wm Kelly on your Matt24:34, taken from BibleHub]
""When its branch has now become tender and the leaves are shooting, ye know that summer is nigh; so likewise ye, when ye shall see all these things, know that it is nigh by the doors" (i.e., the end of this [/the] age, and the beginning of the next under Messiah and the new covenant). But solemnly the Saviour warns that "this generation," this Christ-rejecting race in Israel, shall not pass till all these things be fulfilled!
"The notion that all was fulfilled in the past siege of Jerusalem, founded on a narrow and unscriptural sense of this passage, is from not hearing what the Lord says to the disciples. By the term "generation" in a genealogy (as Matt. 1), or where the context requires it (as Luke 1:50), a life-time no doubt is meant: but where is it so used in the prophetic Scriptures - the Psalms, etc.? The meaning herein is moral rather than chronological; as, for instance, in Psalm 12:7, "Thou shalt keep them, O Lord; Thou shalt preserve them from this generation for ever." The words "for ever" prove a prolonged force; and accordingly the passage intimates that Jehovah shall preserve the godly from their lawless oppressors, "from this generation for ever." It is a distinct and conclusive refutation of those who would limit the phrase to the short epoch of a man's lifetime. So, in Deuteronomy 32:5; Deu 32:20, we find generation similarly used, not to convey a period, but to express the moral characteristics of Israel. Again, in the Psalms we have "the generation to come," which is not confined to a mere term of thirty or a hundred years. So also in Proverbs 30:11-14: "There is a generation that curseth their father. . . There is a generation that are pure in their own eyes," etc., where the character of certain classes is considered; even plainer, if possible, is the usage in the synoptic Gospels. Thus, in Matthew 11:16, "Whereunto shall I liken this generation?" means such as then lived, characterized by the moral capriciousness which set them in opposition to God's testimony, whatever it might be, in righteousness or in grace. But evidently, though people then alive are primarily in view, the moral identity of the same features might extend indefinitely, and so from age to age it would still be "this generation." Compare Matthew 12:39; Mat 12:41-42; Mat 12:45, which last verse shows the unity of the "generation" in its final judgment (not yet exhausted) with that which emerged from the Babylonish captivity. Again, note chapter 23: 36, "Verily I say unto you, All these things shall come upon this generation" - a generation which would continue till all the predictions of judgment that Christ uttered shall be fulfilled (chap. 24: 34). As it is plain from what has been already shown, that much remains to be accomplished, "this generation" still subsists, and will, till all is over. And how true it is! Here are the Jews - the wonder of every thoughtful mind - not merely a broken, scattered, and withal perpetuated race; not only distinct, spite of mighty effort from without to blot them out, and from within to amalgamate with others, but with the same unbelief, rejection and scorn of Jesus their Messiah as on the day He pronounced their sentence. All these things - speaking of their earlier and their latest sorrows - should come to pass before that wicked generation shall disappear. "Heaven and earth shall pass away, but my words shall not pass away." That which incredulity counts most stable, the scene of its idolatry or )f its self-exaltation, shall vanish; but the words of Christ, let them be about Israel or others, shall abide for ever."
[end quoting Wm Kelly; bold, underline and bracketed inserts mine; parentheses original]