"At the current state, the States or People could pass a marriage amendment and the Supreme Court could ruin it, directly or indirectly, say by fiat, defining strangely the terms man and woman for the purposes of legal marriage, or by declaring it's process invalid against some infinite array of arcane details of process."
Words have meaning. If the amendment were written in concise language that any fool can understand, and the Supreme Court refused to recognize it, I believe that at that point it would be prudent for the people to exercise their "right to revolution" as expressed in the Declaration of Independence and hinted at in the 9th amendment to the Constitution.
Not that I am advocating insurrection as we now stand. You submitted a hypothetical and I came up with a hypothetical solution.
People give words meaning, but somehow the words themselves even in their most aethereal ideal and ideation, have an real inertia, a weight that is there independent of the person.
That is, the words --- some words -- are there, anchored, at the most primary level of existance and not mutable by social and personal disposition, climates and times.
Without those absolutist words even kaos, chaos, and the Devil, himself, with Schrodinger's cat cuddled in his arms can naught ever be.