Assyria would be like a tree cut down at the height of its power never to rise again. Judah (the royal line of David) would be like a tree chopped down to a stump. But from that stump a new branch would grow - the Messiah. He would be greater than the original tree and would bear much fruit. The Messiah is the fulfillment of God's promise that a descendant of David would rule forever.
The Messiah is Jesus Christ.
How we long for fair treatment from others, but do we give it? Only Christ can be the perfectly fair judge. Only as he governs our hearts can we learn to be as fair in our treatment of others as we expect others to be toward us.
Judah had become corrupt, and now it was surrounded by hostile foreign powers. The nation desperately needed a revival of righteousness, equity, and faithfulness. They needed to turn from selfishness and show justice to the poor and the oppressed. The righteousness that God values is more than reframing from sin, it is actively turning toward others and offering them the help they need.
It is incredible to think of hostile animals living at peace. It is even more incredible for hostile people to live at peace with one another. And one day the whole world will acknowledge that Christ is Lord.
A golden age is yet to come. Not all of this was fulfilled at Christ's first coming. For example, nature has not returned to its intended balance and harmony.
Reference summary used from The Life Application Bible; Tyndale House Publishers, Inc.; Wheaton, IL