While I was writing the previous post, I happened to look up the process for amending the Constitution, and I noticed something I hadn't registered before. Here's Article V:
The Congress, whenever two thirds of both Houses shall deem it necessary, [blah blah blah] Provided that no Amendment which may be made prior to the Year One thousand eight hundred and eight shall in any Manner affect the first and fourth Clauses in the Ninth Section of the first Article; and that no State, without its Consent, shall be deprived of its equal Suffrage in the Senate.
Huh. If that says what I think it says, it means the Senate in its current form is eternal. Not even a constitutional amendment can eliminate it or reform it unless literally every state agrees. Since 1808 has long since come and gone, that means this is the only absolutely immutable part of our national machinery, the one and only thing that can never be touched. Sort of an odd choice to be given such lofty distinction, no?