The intent of the Senate was to preserve the independence and influence of the states. If you splitline-partition the country, you are eliminating the means of achieving this goal, and it would be simpler to abolish the Senate. It can be argued that the current system of directly electing Senators has already made the institution unrepresentative of the interests of the state governments, but your proposal would further alienate Senators from their home states.
Screw the states. Most of them only exist by historical coincidence anyway, rather than genuine cultural commonality.
I mean, hell, at this point, a lot of "state lines" are either way too far in (resulting in close-by cities within the same broad metro-area having no common government in the Northeast) or way too far out (resulting in close-by cities in the Bay Area having no common government that doesn't also serve rural Central California).
The point of drawing constituency lines is to unite people who have common interests while giving mutual autonomy to people with competing interests. The current states in the USA do none of that: they basically just systematize the shapes of former colonial land-holdings.
There is no constitutional provision that would ever allow abolishing the Senate. The Constitution of the USA prohibits any amendment that could change the disproportionality of the Senate.
An amendment can alter the text of any portion(s) of the constitution. While I agree that abolishing the Senate would be a radical change, I do not know of any restrictions which would bar it.[1] Even if this were not possible, a constitutional convention could be held to make the change.
Technically it says that "no state, without its consent, shall be deprived of its equal suffrage in the Senate" so the Senate could presumably be abolished by constitutional amendment if all states agreed. (I wonder about replacing the Senate with another legislative house and giving the existing Senate largely ceremonial responsibilities without formally abolishing it -- would that count as depriving the states of equal suffrage in the Senate?)
Presumably any amendment that would abolish or sufficiently alter the Senate would simply remove that article as well.
The phrase "the Constitution prohibits this amendment" doesn't make any sense because an amendment to the Constitution cannot by definition be unconstitutional.
