It has been pointed out more than once that, like Jonah’s prophesy of the destruction of Nineveh, Micah’s prophesy of the destruction of Jerusalem was not fulfilled in his lifetime. When the people of Nineveh repented, God gave them another century before razing the city to the ground. When the people of Judah repented, he gave them something like a century and a half.
That doesn’t make Micah’s messages to Judah between 740 and 700 BC or thereabouts, which we have recorded for us here, either irrelevant or inaccurate. It certainly doesn’t mean God’s word was nullified. It just means his pronouncements against Judah came true later rather than sooner.
God’s verdict wasn’t “case dismissed”, it was “judgment delayed”. Chapter 3 gives us a snapshot of the “court proceedings”.