How exactly will the earthly kingdom you believe they will inherit be eternal in light of 2 Peter 3:10-12?
Matthew 25:31-34, 46 KJV
31) 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:
32) And before him shall be gathered all nations: and he shall separate them one from another, as a shepherd divideth his sheep from the goats:
33) And he shall set the sheep on his right hand, but the goats on the left.
34) Then shall the King say unto them on his right hand, Come, ye blessed of my Father, inherit the kingdom prepared for you from the foundation of the world:
( . . . )
46) And these shall go away into everlasting punishment: but the righteous into life eternal.
Jesus does not specify whether He speaks of the 1000 years of His reign, whether He speaks of His kingdom as He does with us in
Colossians 1:13 KJV
Who hath delivered us from the power of darkness, and hath translated us into the kingdom of his dear Son:
These will likewise enter both this kingdom, receiving eternal life, "the righteous into life eternal". This is when they are born again, entering into eternal life, in the eternal kingdom of Jesus Christ, to live as mortals upon the earth, reborn in that day as we are reborn in this day.
These are those who will live on the earth under the rule of Jesus, to populate the nations as Jesus rules from Jerusalem. And the nations will come to Jerusalem to keep the feast, lest they not receive rain.
Their children will have to make their own choice to obey Jesus or resist Him, though resistance will bring grave consequence. Jesus will rule with a rod of iron.
And at the end of the 1000 years, they will have children filling the earth, and Satan will be loosed a short season to deceive them, and to gather them against "the camp of the saints, and the beloved city", only to be destroyed by fire from heaven.
You asked regarding
2 Peter 3:9-12 KJV
9) The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance.
10) But the day of the Lord will come as a thief in the night; in the which the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up.
11) Seeing then that all these things shall be dissolved, what manner of persons ought ye to be in all holy conversation and godliness,
12) Looking for and hasting unto the coming of the day of God, wherein the heavens being on fire shall be dissolved, and the elements shall melt with fervent heat?
The Day of YHWH, the Day of God, would you like to share a study through the Bible of how it speaks of the Day of the LORD? There are various ways people look at "Day of the LORD", and those different ways have a lot to do with how they understand other passages.
Ezekiel 30 describes the "Day of YHWH" upon Egypt,
Ezekiel 30:2-4 KJV
2) Son of man, prophesy and say, Thus saith the Lord GOD; Howl ye, Woe worth the day!
3) For the day is near, even the day of the LORD is near, a cloudy day; it shall be the time of the heathen.
4) And the sword shall come upon Egypt, and great pain shall be in Ethiopia, when the slain shall fall in Egypt, and they shall take away her multitude, and her foundations shall be broken down.
as God takes away Egypt's allies, and
Ezekiel 30:10 KJV
Thus saith the Lord GOD; I will also make the multitude of Egypt to cease by the hand of Nebuchadrezzar king of Babylon.
While the "Day of YHWH" seems to me to be primarily used for the end time of God's judgment of the world, it's clearly not exclusively that. So we need to look at that.
Does "Day of YHWH" mean specifically a 24 hour day? Ground wars like Babylon conquering Egypt typically happen as campaigns, with armies advancing day by day across the land, and the prophetic account in Ezekiel reads just like that, even to the point of saying,
Ezekiel 30:16-18 KJV
16) And I will set fire in Egypt: Sin shall have great pain, and No shall be rent asunder, and Noph
shall have distresses daily.
17) The young men of Aven and of Pibeseth shall fall by the sword: and these cities shall go into captivity.
18) At Tehaphnehes also the day shall be darkened, when I shall break there the yokes of Egypt: and the pomp of her strength shall cease in her: as for her, a cloud shall cover her, and her daughters shall go into captivity.
Daily distresses, and finally ending at Tehaphnehes, where Egypt is conquered.
There are a number of other places to look at to see exactly how the Bible speaks of this particular Day.
Much love!