This World is of my Kingdom

I agree, the world is already of His Kingdom, but they are currently occupied by the devil:

The devil took Him to a very high mountain and showed Him all the kingdoms of the world and their glory. “All this I will give You,” he said, “if You will fall down and worship me.” Matthew 4:8-9

Yet the Most High is still in control, as Yeshua said to Pilate:

You would have no authority over me at all unless it had been given you from above John 19:11

Yeshua will not receive the kingdoms of the world by submission to the devil, but by submission to God and by conquest:

And the seventh angel sounded; and there were great voices in heaven, saying, The kingdoms of this world are become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever. Revelation 11:15

God will give him the throne of David:

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: and he shall reign over the house of Jacob for ever; and of his kingdom there shall be no end. Luke 1:32-33