The prophet presents King Zedekiah with a final, clear warning regarding the future. The survival of the royal family, the king himself, and the entire city hinges completely on a single choice: whether to surrender and make peace with the Babylonians. Yielding to the enemy is the only path to stay alive and avert total destruction.
If the king refuses, his wives and children will be led out to the Chaldean camp stationed just outside the city walls. There are different possibilities regarding who will physically force the royal family out. They might be handed over by the city's own soldiers or residents, or the Chaldean troops themselves might enter the conquered city and drag the royal family out to their comrades waiting beyond the walls [רד״ק, ביאור שטיינזלץ, מצודת דוד]. The king himself will find no means of escape and will be physically seized by force [מצודת ציון].
The warning culminates with the declaration that the king will burn the city with fire. Commentators agree that the king will not literally ignite the flames himself. Rather, the destruction is attributed directly to him because he is the root cause of the tragedy. By refusing to listen to the voice of God spoken through a true prophet [חומת אנך] and rejecting the call to surrender to the Chaldeans [מצודת דוד, רד״ק], the king bears full personal responsibility. Ultimately, his choices make him so responsible for the disaster that it is considered as if he burned the city to the ground with his own hands [רש״י].