I disagree with you perception of a future throne for Jesus Christ, as he sits upon this throne currently, the work of Calvary is finished.
The work of Calvary is finished and Jesus now sits at the right hand of the Father making intercession for us.
The Davidic Covenant and the promises of God concerning the Messianic kingdom has not yet been fulfilled, but will be when the seventh angel sounds its trumpet and the kingdoms of this world will then become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever, Rev 11:15. When Christ sits on the throne of David it will be an earthly ruling authority for all eternity within the New Jerusalem.
Revelation 3:21 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.
Matthew 19:28 And Jesus said unto them, Verily I say unto you, That ye which have followed me, in the regeneration when the Son of man shall sit in the throne of his glory, ye also shall sit upon twelve thrones, judging the twelve tribes of Israel.
Luke 1:30 And the angel said unto her, Fear not, Mary: for thou hast found favour with God. 31 And, behold, thou shalt conceive in thy womb, and bring forth a son, and shalt call his name JESUS. 32 He shall be great, and shall be called the Son of the Highest: and the Lord God shall give unto him the throne of his father David: 33 And he shall reign over the house of Jacob for ever; and of his kingdom there shall be no end.
Luke 22:15 And he said unto them, With desire I have desired to eat this passover with you before I suffer: 16 For I say unto you, I will not any more eat thereof, until it be fulfilled in the kingdom of God. 17 And he took the cup, and gave thanks, and said, Take this, and divide it among yourselves: 18 For I say unto you, I will not drink of the fruit of the vine, until the kingdom of God shall come.
Acts 2: 33 Therefore being by the right hand of God exalted, and having received of the Father the promise of the Holy Ghost, he hath shed forth this, which ye now see and hear. 34 For David is not ascended into the heavens: but he saith himself, The Lord said unto my Lord, Sit thou on my right hand, 35 Until I make thy foes thy footstool. 36 Therefore let all the house of Israel know assuredly, that God hath made that same Jesus, whom ye have crucified, both Lord and Christ.