The prophecy delivers a stark and ironic twist to the arrogant confidence of Jerusalem's leaders. These men had proudly compared their fortified city to a sturdy cooking pot and themselves to the meat inside it. They firmly believed that just as a pot shields its contents from the fire, the city walls would protect them from their enemies, allowing them to live out their days in absolute safety and avoid exile [רד"ק, מלבי"ם].
God shatters this illusion, warning them that their chosen metaphor will indeed come true, but in a horrifyingly reversed manner. The primary approach among commentators is that the only people who will remain permanently in the city are the innocent victims these very leaders have murdered. The corpses of the slain are the true meat, and Jerusalem will serve merely as the pot that contains their remains.
As for the corrupt leaders themselves, their hopes of clinging to the homes they built are entirely in vain. Because they and their children are destined for exile, there will be no one left to inherit their wealth or property [רש"י]. Far from remaining safely within the city walls, they will face a harsh divine decree. God will bring a sword against them, forcibly expel them from their supposed sanctuary, and drag them into exile against their will [רש"י, רד"ק, מצודות, מלבי"ם].