"My kingdom is not of this world.."
There is no trace of the old kingdom of Israel. Jesus said that the prophecies in the old Testament spoke of him. His kingdom, which was bestowed upon him by God at his death and resurrection, has no end. He never promised an earthly kingdom.
The language you are quoting is figurative, not literal. If we read prophecy like that, then we have to reject John the Baptist as Elijah since he never moved any literal mountains or valleys.
do not be led into every wind of doctrine...in Jer 31 when the new covenant was promised have you read the rest of the chapter?
35 Thus says the LORD,
Who gives the sun for a light by day,
The ordinances of the moon and the stars for a light by night,
Who disturbs the sea,
And its waves roar
(The LORD of hosts
is His name):
36 “If those ordinances depart
From before Me, says the LORD,
Then the seed of Israel shall also cease
From being a nation before Me forever.”
37 Thus says the LORD:
“If heaven above can be measured,
And the foundations of the earth searched out beneath,
I will also cast off all the seed of Israel
For all that they have done, says the LORD.
38 “Behold, the days are coming, says the LORD, that the city shall be built for the LORD from the Tower of Hananel to the Corner Gate. 39 The surveyor’s line shall again extend straight forward over the hill Gareb; then it shall turn toward Goath. 40 And the whole valley of the dead bodies and of the ashes, and all the fields as far as the Brook Kidron, to the corner of the Horse Gate toward the east,
shall be holy to the LORD. It shall not be plucked up or thrown down anymore forever.”
In this section which immediately follows the promise of a new covenant God reaffirms twice that Israel will not cease to be a nation in His eyes. Now Jesus wept for Jerusalem and predicted their destruction. God alone knows the future so the placing of this promise right after the event that would precede their destruction is by design. The end of the chapter speaks of clearly Jerusalem noting it will be built and holy from a time when dead bodies are piled up and that it will not be thrown down anymore. Look at Zech 14 we see Jerusalem is being overrun and the LORD fights and kills many enemies and then life is seen continuing after the LORD is king over all the earth.
also note Jeremiah points out that in the new covenant God will forgive sins and give them a new heart and write His laws in their hearts and minds and He will be there God. Now Israel did not receive Jesus and the church was born into the new covenant. But God reaffirms this exact promise and experience to national Israel and even notes that this promise is to those who have been gathered back from all the nations where God has scattered them. Eze 36 you should read ch 36-40 but in 36
For indeed I
am for you, and I will turn to you, and you shall be tilled and sown. 10 I will multiply men upon you, all the house of Israel, all of it; and the cities shall be inhabited and the ruins rebuilt. 11 I will multiply upon you man and beast; and they shall increase and bear young; I will make you inhabited as in former times, and do better
for you than at your beginnings. Then you shall know that I
am the LORD. 12 Yes, I will cause men to walk on you, My people Israel; they shall take possession of you, and you shall be their inheritance; no more shall you bereave them
of children.”
13 ‘Thus says the Lord GOD: “Because they say to you, ‘You devour men and bereave your nation
of children,’ 14 therefore you shall devour men no more, nor bereave your nation anymore,” says the Lord GOD. 15 “Nor will I let you hear the taunts of the nations anymore, nor bear the reproach of the peoples anymore, nor shall you cause your nation to stumble anymore,” says the Lord GOD.’ ”.....
2 “Therefore say to the house of Israel, ‘Thus says the Lord GOD: “I do not do
this for your sake, O house of Israel, but for My holy name’s sake, which you have profaned among the nations wherever you went. 23 And I will sanctify My great name, which has been profaned among the nations, which you have profaned in their midst; and the nations shall know that I
am the LORD,” says the Lord GOD, “when I am hallowed in you before their eyes. 24 For I will take you from among the nations, gather you out of all countries, and bring you into your own land. 25 Then I will sprinkle clean water on you, and you shall be clean; I will cleanse you from all your filthiness and from all your idols. 26 I will give you a new heart and put a new spirit within you; I will take the heart of stone out of your flesh and give you a heart of flesh. 27 I will put My Spirit within you and cause you to walk in My statutes, and you will keep My judgments and do
them. 28 Then you shall dwell in the land that I gave to your fathers; you shall be My people, and I will be your God.
I am taking all these passages and they are congruent taken literally and in the future sense. The 3rd temple is coming and the abomination of desolation is going to take place. Jesus notes that Israel will be desolate and yet one day this will happen. 37 “O Jerusalem, Jerusalem, the one who kills the prophets and stones those who are sent to her! How often I wanted to gather your children together, as a hen gathers her chicks under
her wings, but you were not willing! 38 See! Your house is left to you desolate; 39 for I say to you, you shall see Me no more till you say,
‘Blessed is He who comes in the name of the LORD!’ ”. This is the LORD coming in Zech 14, Dan 2 7 and finishing the 70th week of Daniel.