The prophetic warning shifts from a broad picture of national disaster to a direct, intensely personal message aimed at the King of Assyria. God issues a harsh decree that permanently seals the fate of the king, his royal dynasty, and his legacy.
Using the imagery of planting and growth, the decree declares an end to the king's royal line. The primary approach among commentators is that the king will leave behind no heirs to continue his rule or carry on his name. He and his descendants will be completely wiped out. [רד״ק] notes the historical reality of this downfall, explaining that the king's own sons attacked him with a sword and fled, abruptly ending the royal succession.
The downfall takes on a deeply ironic twist, occurring in the very place the king considered most sacred. The primary approach among commentators is that the king will flee to his pagan temple seeking safety, only to meet his death right there. By dying in his place of worship, the building itself transforms into his grave. This violent end strips the site of its supposed holiness, destroys the idols within, and leaves the area an abandoned wasteland [רש״י, רד״ק, אבן עזרא, מצודת דוד]. Offering a different perspective, [מלבי״ם] explains that ancient kings would often place statues of themselves inside their temples to receive divine honors. God will tear down these monuments of glory, replacing them with a monument of shame upon the king's grave to stand as a lasting witness to his defeat.
This total collapse happens because the king became despised and completely insignificant in the eyes of God [רש״י, שטיינזלץ]. His disgrace stems from his arrogant foolishness, as he dared to insult God by claiming He could not save Jerusalem [מצודת דוד, רד״ק]. Furthermore, the sheer humiliation of being murdered by his own children inside his personal place of worship serves as the ultimate mark of shame [רד״ק]. Taking a different approach, [מלבי״ם] connects the description of the king's ruin to the concept of roasting, suggesting that his final punishment will be to be entirely consumed by fire.