Beyond the messianic reference in the scepter prophecy (Genesis:49:10), God gave many other prophecies about the Messiah in Scripture.
He was to be of the line of David, ruling on David’s throne (see Isaiah:9:6-9). And Jesus Christ, as the Messiah, was to fulfill these prophecies, as God was to "give Him the throne of His father David" (Luke:1:31-33). Indeed, Jesus was physically descended—through His mother Mary—from David’s son Nathan (Romans:1:3; Luke:3:23, 30-33, Heli of that lineage being the father of Mary and father-in-law of her husband Joseph).
Mary’s husband Joseph was himself of the Solomonic line of Jeconiah, and Jesus was reckoned as his son, signifying Jesus’ adoption by him (Matthew:1:1-16; compare Luke:2:48). This adoption could perhaps have given Jesus a legal claim to the throne. Yet remarkably, if He had been the actual son of Joseph, descent from Jeconiah would have barred Him from inheriting David’s throne. But Jesus was not Joseph’s son—He was the Son of God the Father through miraculous conception in the womb of Mary when she was yet a betrothed virgin. And through Mary, Jesus was descended from David by a different family line, as mentioned.
Furthermore, Christ, "the Lion of the tribe of Judah" (Revelation:5:5), is both "the Root and the Offspring of David" (3:16). That is, beyond being David’s descendant, Jesus was also the ancestor of David, as the Eternal God who created Adam—the father of all mankind (Luke:3:38; compare Ephesians:3:9). Moreover, the preincarnate Jesus was Israel’s first King. The Davidic throne was actually, as we’ve seen, the throne of the Lord. And since Jesus is the Lord, the throne ultimately remained His to take back.
Many will hail these facts as proof that God’s promises to David have been fulfilled in Christ’s coming as David’s descendant. Yet if so, it still doesn’t explain why there wasn’t a reigning king of David’s line for more than 500 years between Zedekiah and Jesus. David’s throne was supposed to be occupied in "all generations." And yet it would appear that there wasn’t even a Davidic throne or kingship in existence for all that time. How did Christ inherit a throne that didn’t exist?
The truth of the matter is that Jesus did not sit on David’s throne when He came in the flesh—nor has He at anytime since. In a parable, Christ portrays Himself as a nobleman who "went to a far country to receive for himself a kingdom and to return" (Luke:19:12)—that is, He went to heaven to receive the Kingdom of God and has not yet returned to rule over it. Jesus is presently sitting with the Father on His throne in heaven (Revelation:3:21; Hebrews:12:2). But since Christ’s rule over all nations from Jerusalem (see Jeremiah:3:17) has not yet begun, does that mean more than 2,500 years have gone by without a descendant of David reigning as king? Has God broken His word after all?
One important factor often overlooked about the scepter prophecy in Genesis:49:10 is that it shows Judah still having a ruling monarch, waiting for the Messiah to take over, "in the last days" (verse 1). Therefore, since Jesus has not yet returned in power and glory, there must be a monarch of Jewish descent reigning somewhere on the earth during this generation. In fact, that monarch must be of the line of David, occupying a throne that has continued through all generations since David. Otherwise, the Bible is unreliable.