NOTES for Mic 5:3
With the Messiah, Micah, like other prophets (especially the pre-exilic ones), connects the gathering of God's people, who in the days of the Messiah will again gather in the land of their fathers, united around Jerusalem. By those "abandoned for a time," the prophet evidently means that part of the people which, after the defeat of the Northern (Israelite) kingdom, found itself scattered throughout the vast Assyrian Empire: this scattering was perceived, and not without reason, as evidence of being abandoned by God, as God's punishment for that part of the people that had betrayed the God of their fathers.
It should be noted that in the south, in Judah, the rulers of the Northern Kingdom were regarded as apostates. There were grounds for this: in their country they pursued a policy of religious double allegiance, and in fact of paganism, officially recognizing a whole series of pagan cults as state cults alongside the cult of YHWH. Many in Judah looked at the defeat of the Northern Kingdom as the natural result of this policy. But it appears that it had been revealed to the prophet that in the history of God's people a day would come when the Messiah would arrive and the fullness of the people would be restored.
Of course, Micah sees this restoration as a process more political than spiritual. But prophetic perception of spiritual reality is always multilayered, and behind historical, social, or political reality there always stands spiritual reality. So here too: Micah sees a spiritual process as a political and national process. He sees renewed Israel as it would be if, by some sudden miracle, the brilliant era of Solomon were to return.
And the era of the Messiah truly was brilliant, though not in the sense in which the prophet speaks of it, even if even the apostles on the day of the Ascension were still expecting an outward triumph, expecting "the restoration of the kingdom to Israel." The Kingdom turned out not to be what the pre-exilic prophets had seen. And the King, too, turned out not to be what many expected to see, not only in Micah's time but also in the Gospel era.
But the fullness of God's people truly was revealed. To be sure, it came without outward greatness, without a strong state led by heroic rulers. It came in the Kingdom which, according to the King's word, is "not of this world." And that does not make it any less majestic.