The future downfall of the Babylonian empire establishes a clear principle of historical justice: those who enslave others will eventually become enslaved themselves. Just as Babylon forced other nations into submission, it is destined to suffer the exact same fate. The vast powers and great kings that will eventually conquer and rule over Babylon are the empires of Media and Persia [רש״י, רד״ק, ביאור שטיינזלץ]. This justice is highly specific, as the nations that will subjugate Babylon are the very same ones that previously suffered under its crushing power, allowing them to directly return all the harm that was done to them [מלבי״ם].
God promises an exact, measure-for-measure punishment for the Babylonians, addressing every aspect of their wrongdoing. This divine retribution targets two distinct layers of their crimes [מלבי״ם]. First, they will face justice for the final outcome and the sheer physical destruction they left in their wake. Second, God will punish them for the internal process of their actions. The Babylonians will be held accountable not merely for the tangible damage they caused to others, but also for the deep cruelty, jealousy, and anger that fueled their conquests.