"But when the 70 years are over, I shall punish the king of Babylon and that nation, Yahweh declares, for the wrong they have done, that is, the country of the Chaldeans, and make it desolate forever ( or times indefinite)."
It's the GENERATION doctrine at work.
Chaldea as described by Wikipedia as geography:
It is impossible to define narrowly the boundaries of this early land of Chaldea, and one may only locate it generally in the low, marshy, alluvial land about the estuaries of the Tigris and Euphrates, which then discharged their waters through separate mouths into the sea. In a later time, when the Chaldean tribe had burst their narrow bonds and obtained the ascendency over all Babylonia, they gave their name to the whole land of Babylonia, which then was called Chaldea for a short time.
Rulers of Babylon when Cyrus attacked:
The End of the Chaldean Dynasty
Neriglissar succeeded Amel-Marduk. It is unclear as to whether he was in fact a Chaldean or a native Babylonian nobleman, as he was not related by blood to Nabopolassar's descendants. He conducted successful military campaigns against the Hellenic inhabitants of Cilicia, which had threatened Babylonian interests. Neriglissar however reigned for only four years, being succeeded by the youthful Labashi-Marduk in 560 BC. Again it is unclear as to whether he was a Chaldean or a native Babylonian.
Labashi-Marduk reigned only for a matter of months, being deposed by Nabonidus in late 560 BC. Nabonidus, was certainly not a Chaldean, ironically he was an Assyrian from Harran, the last capital of Assyria. Nabonidus proved to be the final native Mesopotamian king of Babylon, he and his son, the regent Belshazzar being deposed by the Persians in 539 BC.
---------------
This is how Sennacherib surveyed the situation, from an on-line book by George Godspeed, drawn from stella translations.
In 2 Kings 20 and Isaiah 38 and 39, the narrative only touches on the beginning of this story with the emissaries to Hezekiah from Merodach-Baladan. As Hezekiah speaks of hopes of peace with Babylon, Isaiah speaks with bitter irony. Perhaps it was 703 BC, but he does not speak of what is about to befall Babylon.
(722 BC – 710 BC, 703 BC – 702 BC) Marduk-apla-iddina II,
(the biblical Merodach-Baladan, also called Marduk-Baladan, Baladan and Berodach-Baladan, lit. Marduk has given me an Heir.) a Chaldean prince who usurped Babylonian throne in 721 BC. Also known as one of the kings who maintained Babylonian independence in the face of Assyrian military supremacy for more than a decade. Sargon of Assyria repressed the his allies in Elam, Aram and Israel and eventually drove (ca. 710 BC) him from Babylon. After the death of Sargon, he briefly recaptured the throne from a native Babylonian nobleman, reigning 9 months (703 BC – 702 BC). He returned from Elam and ignited rebellion in Babylonia. He was able to enter Babylon and be declared king again. Nine months later he was defeated near Kish by the Assyrians, but managed to flee to Elam. He died in exile a couple of years later.
(703-700 BC) Bel-ibni
a Babylonian nobleman who served as King of Babylon for several years as the nominee of the Assyrian king Sennacherib.
Sennacherib, believing that direct Assyrian rule was too costly, appointed Bel-ibni, a young Babylonian nobleman raised at the Assyrian court, King of Babylon in 703 BC. The experiment with a native puppet king was hardly more successful than direct Assyrian control. Soon Bel-ibni was conspiring with the Chaldeans and Elamites against the Assyrians. After defeating the opposing coalition in 700 BC, Sennacherib deposed Bel-ibni and carried him off to Assyrian exile, replacing him with Sennacherib's own son, Ashur-nadin-shumi.
(700-694 BC) Ashur-nadin-shumi
(d.694 BC) was an ancient King of Babylon. The son of the Assyrian king Sennacherib, Ashur-nadin-shumi was installed by his father as King of Babylon in 700 BC. He reigned for six years, until he was murdered by the Elamites following their capture of the city in 694 BC.
(694-693) Nergal-ushezib, originally Shuzub,
a Babylonian nobleman who was installed as King of Babylon by the Elamites in 694 BC, after their capture of Babylon and deposition and murder of the previous king Ashur-nadin-shumi, son of King Sennacherib of Assyria.
Reigned as King for little more than a year. Sennacherib soon made war on Babylon to recover the city and avenge his son's death. Nergal-ushezib was defeated and captured by the Assyrians in battle near Nippur in September 693 BC. His subsequent fate is unknown. He was succeeded by the Chaldean prince Mushezib-Marduk, who continued the resistance against Assyria.
(692 - 689 BC), Mushezib-Marduk
Chaldean prince chosen as King of Babylon after Nergal-ushezib. He led the Babylonian populace in revolt against Assyria and King Sennacherib in 689 BC, with the support of Elam and King Humban-nimena (which was attacked by the Babylonians and the Assyrians only years before), at the Battle of Halule. It's not clear who won this battle, since both sides claimed victory, and all rulers remained on their thrones, but it is generally agreed that the Assyrians suffered the greatest losses.
Mushezib-Marduk lost his ally when the Elamite king Humban-nimena suffered a stroke later that same year, an opportunity King Sennacherib quickly seized by attacking Babylon, and eventually capturing it after a nine-month siege. To avenge the death of his son, whom the Babylonians had effectively killed when they handed him over to the Elamites in 694 BC, Sennacherib pillaged and burned Babylon, tore down its walls, and even diverted the Euphrates into the city. During the Sack of Babylon, Mushezib-Marduk was most likely murdered.
(689-681) Sennacherib…succeeded by Esarhaddon
228. Whatever arrangements Sennacherib had made for the government in Babylon, on the fall of the usurper, were speedily brought to naught by the Babylonians themselves, who made the Kaldean prince Shuzub (sect. 226) their king, under the name of Mushezib Marduk (693 B.C.). ... Mushezib Marduk knew that his turn would soon come for punishment, and made a vigorous effort to defend himself. He called for aid upon the new Elamite king, who for his own security must also show a bold front to Assyria. The Babylonians likewise felt that vengeance would fall upon them for their treachery, and committed an act which revealed their desperate fear and hatred of Sennacherib. They opened the treasuries of the temples, and offered the wealth of Marduk for the purchase of Elamite support. All through the winter of 692 B.C. the preparations went on to meet the Assyrian advance.
A great army of Elamites, Arameans, Babylonians, and Kaldeans was gathered. Sennacherib compared its advance to "the coming of locust-swarms in the spring." "The face of the heavens was covered with the dust of their feet like a heavy cloud big with mischief." The battle was joined at Khalule, on the eastern bank of the Tigris, in 691 B.C., and, after a long and fierce struggle, the issue was drawn. Sennacherib claimed a victory, but, though the coalition was broken, his own forces were so shattered that he advanced no farther, and left to Mushezib Marduk the possession of the Babylonian throne for that year.
229. During the next two years Sennacherib grappled with the Babylonian problem and brought it to a definite solution. On his advance in 690 B.C. he met with no serious opposition. Ummanmenanu of Elam could offer no aid to Mushezib Marduk, who was speedily seized and sent to Nineveh. Babylon now lay at the mercy of the Assyrian, whose long-tried patience was exhausted. He determined on no less a vengeance than the total destruction of the ancient city. The work was systematically and thoroughly done. The temples and palaces were levelled. Fortifications and walls were uprooted. The inhabitants were slaughtered; even those who sought refuge in the temples perished. Images of Babylonian gods were not spared. Two images of Assyrian deities, which Marduknadinakhi had carried away from Ekallati (sect. 145), were carefully removed and restored to their city. The canal of Arakhtu was turned from its bed so as to flow over the ruins. The immense spoil was made over to the soldiers. The district was then placed under a provincial government, as had already been the case with the lands of the Kaldeans and Arameans round about it. Sennacherib thus ruled Babylon till his death. The Babylonian kings' list names him as "king" both for the years 705-703 B.C. and also during this last period, 689-681 B.C., although the source from which Ptolemy drew his information denominated both these periods "kingless." The Assyrian had made a solitude and called it peace.
----