The references to the “Throne of David” should not be taken as a literal reference to a wooden chair. The literal “throne of david” was either burned or turned to dust many centuries ago.
Rather, the “throne of David” refers to his seat of authority. It is clear that this belongs to Jesus, so the only question that remains for some is whether it must pertain to Jerusalem somehow. While it is clear that Jerusalem has a special purpose, it is also sufficiently clear that Jerusalem could never fulfill the prophecies of the Throne of David. Rather, the Throne of David, just like the thrones of other nations and regions, are spiritual entities, as described by Paul (Colossians 1:16).
Any other rendering of the text would imply that Jesus Christ was not reigning right now in that stead. Since it is given in Matthew 28:18 that He now has all authority, and in Ephesians 1:19-20 that He is already above every name and title that could possibly be given, it seems a fairly foregone conclusion that this must be, or include, the throne of David. You cannot give anything to the one who has all, and you cannot promote anyone who has already been raised above everything.
Clearly, the throne of David will have a bearing on Jerusalem, but the Kingdom is Eternal, and heaven and Earth will pass away.
God endowed David with a measure of authority, and that authority constitutes David’s throne and legacy. As David ruled in that throne, he established it, even as the foundation of God’s throne is righteousness and justice.
So, David’s throne, being ordained and anointed by God, was a heavenly reality, as God’s original purpose for man was to rule and reign on the Earth (Genesis 1:28). It was this throne, not a physical, wooden chair in a brick and mortar building, which constitutes David’s throne, the earthly seat of God’s Kingdom, in both the Old Covenant and the New. And, it is this throne that Jesus Christ right now controls, in the heavens.