Some standing in the crowd that Jesus is talking to that was still alive when he returned to earth:
[Mat 16:28 KJV] Verily I say unto you, There be some standing here, which shall not taste of death, till they see the Son of man coming in his kingdom.
[Mar 9:1 KJV] And he said unto them, Verily I say unto you, That there be some of them that stand here, which shall not taste of death, till they have seen the kingdom of God come with power.
[Luk 9:26 KJV] For whosoever shall be ashamed of me and of my words, of him shall the Son of man be ashamed, when he shall come in his own glory, and [in his] Father’s, and of the holy angels.
[Luk 9:27 KJV] But I tell you of a truth, there be some standing here, which shall not taste of death, till they see the kingdom of God.
[1Th 4:15-17 KJV] For this we say unto you by the word of the Lord, that we which are alive [and] remain unto the coming of the Lord shall not prevent them which are asleep. 16 For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first: 17 Then we which are alive [and] remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord.
That generation did not pass:
[Mat 24:34 KJV] 34 Verily I say unto you, This generation shall not pass, till all these things be fulfilled.
[Mar 13:30 KJV] 30 Verily I say unto you, that this generation shall not pass, till all these things be done.
[Luk 21:32 KJV] 32 Verily I say unto you, This generation shall not pass away, till all be fulfilled.
What we know about the 1000 Years
[Rev 20:2-6 KJV]
And he laid hold on the dragon, that old serpent, which is the Devil, and Satan, and bound him a thousand years, And cast him into the bottomless pit, and shut him up, and set a seal upon him, that he should (1)deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little season. 4 And I saw thrones, and they sat upon them, and judgment was given unto them: and [I saw] the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received [his] mark upon their foreheads, or in their hands; and (2) they lived and reigned with Christ a thousand years. 5 But the (3) rest of the dead lived not again until the thousand years were finished. This [is] the first resurrection. 6 Blessed and holy [is] he that hath part in the first resurrection: on such the second death hath no power, but (4)they shall be priests of God and of Christ, and shall reign with him a thousand years.
(1) Satan deceive the nations no more in the 1000 years.
(2) they lived and reigned with Christ a thousand years
(3) Rest of the dead lived again after the 1000 years
(4) they shall be priests of God and of Christ, and shall reign with him a thousand years.
Christ Rules With Iron Rod
[Psa 2:9 KJV] 9 Thou shalt break them with a rod of iron; thou shalt dash them in pieces like a potter’s vessel.
[Rev 2:27 KJV] 27 And he shall rule them with a rod of iron; as the vessels of a potter shall they be broken to shivers: even as I received of my Father.
[Rev 12:5 KJV] 5 And she brought forth a man child, who was to rule all nations with a rod of iron: and her child was caught up unto God, and [to] his throne.
[Rev 19:15 KJV] 15 And out of his mouth goeth a sharp sword, that with it he should smite the nations: and he shall rule them with a rod of iron: and he treadeth the winepress of the fierceness and wrath of Almighty God.
Gods Throne
God’s Throne is in Heaven
[Heb 8:1 KJV] Now of the things which we have spoken [this is] the sum: We have such an high priest, who is set on the right hand of the throne of the Majesty in the heavens;
[Mat 5:34 KJV] But I say unto you, Swear not at all; neither by heaven; for it is God’s throne:
[Heb 12:2 KJV] Looking unto Jesus the author and finisher of [our] faith; who for the joy that was set before him endured the cross, despising the shame, and is set down at the right hand of the throne of God.
[Rev 3:21 KJV] To him that overcometh will I grant to sit with me in my throne, even as I also overcame, and am set down with my Father in his throne.
[Rev 4:2 KJV] And immediately I was in the spirit: and, behold, a throne was set in heaven, and [one] sat on the throne.
[Act 7:49 KJV] Heaven [is] my throne, and earth [is] my footstool: what house will ye build me? saith the Lord: or what [is] the place of my rest?
Jesus Throne on Earth
[Mat 25:31 KJV] When the Son of man shall come in his glory, and all the holy angels with him, then shall he sit upon the throne of his glory:
Rev 20:4 KJV – And I saw thrones, and they sat upon them, and judgment was given unto them: and [I saw] the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received [his] mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years.
Rev 20:6 KJV – Blessed and holy [is] he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years.
As per above the saints lived and reigned with Christ on earth.
New Jerusalem

When does New Jerusalem come down from heaven?
Rev 21:1-2 KJV – And I saw a new heaven and a new earth: for the first heaven and the first earth were passed away; and there was no more sea. And I John saw the holy city, new Jerusalem, coming down from God out of heaven, prepared as a bride adorned for her husband.
As per above verse the holy city New Jerusalem only comes down from heaven to earth on the new heaven and earth; when we have NO MORE SEA.
The throne of God and the Lamb shall be in this New Jerusalem on earth
[Rev 22:3 KJV] 3 And there shall be no more curse: but the throne of God and of the Lamb shall be in it; and his servants shall serve him: