The Chaldean Empire was ruled from Babylon until that fateful night recorded in Daniel 5. After the death of Belshazzar, it staggered on a few years, but the relatively bloodless conquest of the empire’s capital city effectively signaled the rise of the Medo-Persians to the world stage. Cyrus quickly subdued his Median allies and moved on to other conquests, making the Persian Empire the virtually uncontested world power for the next 200 years or so.
This well-established historical note makes the last few verses of Haggai all but impossible to apply to Zerubbabel personally, though there are certainly those who will try.