Then it would be part of the Constitution. It would be the law of the land.
A duly-adopted amendment becomes part of the Constitution. Amending means changing. Adding or subtracting. The Constitution cannot, by definition, be unconstitutional. Am I speaking Esperanto here?
Don't talk to me about original intent -- the Founders' original intent was that the runner-up for president would be the vice president. The folks who actually had to govern fixed that in a hurry. They amended the Constitution. Changed it. It's been done 27 times in the last 220 years. An amendment isn't an editorial or an oh-by-the-way. It is part of the Constitution. Full stop.
I’m going by the plain language of the document—no need to divine “original intent.” There is a proviso limiting the amendment process (end of Article V) explicitly saying “that no State, without its Consent, shall be deprived of its equal Suffrage in the Senate.”