As did James Madison. I think that the implication is that a state may leave by the same manner as states join - a simple majority vote in both Houses of Congress. No super majority, no amendment, just a vote.
Hard to be the U.S. Senator from Texas is Texas has left the U.S.A.
My dad used to support secession because the Constitution was a contract that was freely entered into. I argued that ALL contracts are freely entered into, but they are still binding until a remedy is exercised within that contract.
The “remedy” within the “contract” of the U.S. Constitution would be a vote by Congress passed by the President (or overriding of his veto).
Great point.