Jamelle Bouie writes in the Times this week that the antifederalists saw this coming:
So too could the earliest critics of the Constitution. In talking and thinking about impeachment, observers and participants have gone on (and on) about the founding fathers: about Hamilton and Madison and the Federalist Papers. But their opponents, the antifederalists, also thought about the process. In their fight against the Constitution, they covered every inch of the new governing document, touching every section, every article and every clause. Looking from the perspective of now — one week into the impeachment trial — it’s striking to see how, without knowledge of political parties or partisan factionalism, they captured the exact dynamic that will keep a corrupt president in office.
The Senate was a sticking point for the antifederalists. With its small membership and fixed terms, they thought it was too aristocratic; with its mix of legislative, executive and judicial powers, they thought it was too powerful. “Is a body so vested with means to soften and seduce — so armed with power to screen or to condemn — so fortified against suspicion and enquiry — so largely trusted with legislative powers — so independent of and removed from the people — so tempted to abuse and extend those powers — is this a body which freeman ought ever to create, or which freeman can ever endure?” the writer “Cincinnatus” asked in reply to James Wilson, a key delegate to the Constitutional Convention.
The haze of time is thick, but I don't remember my US History teacher in high school talking much about the antifederalists. I should ask Danny if his teacher covered it this year.
The other thing I don't think any faction foresaw back then, perhaps reasonably, was a future where some states would have 40 million people, and others would have 600,000. If they had, that would have been an even stronger argument against structuring the Senate as it is.