Two separate issues - the permanence of the union upon ratification and the methodology of disunion.
Chase wrote, 'What can be indissoluble if a perpetual Union, made more perfect, is not? ... The Constitution, in all its provisions, looks to an indestructible Union, composed of indestructible States. ... When, therefore, Texas became one of the United States, she entered into an indissoluble relation.
Via amendment the entire union could be dissolved. That crushes Chases' "indissoluble" and "indestructible" characteristics. We have already proven that "perpetual" simply means without a stated end, not "permanent". Regarding an "indestructible union" composed of indestructible States, Article IV§3 destroys that absurd holding. Lastly, nothing in the Constitution prevents a state from leaving, it actually guarantees them that right. The states were sovereign under the Articles, and to paraphrase Chase, 'What can be more sovereign, than a state made more perfect?'
Continue please. Chase went on to say, "...The Constitution, in all its provisions, looks to an indestructible Union, composed of indestructible States. When, therefore, Texas became one of the United States, she entered into an indissoluble relation. All the obligations of perpetual union, and all the guaranties of republican government in the Union, attached at once to the State. The act which consummated her admission into the Union was something more than a compact; it was the incorporation of a new member into the political body. And it was final. The union between Texas and the other States was as complete, as perpetual, and as indissoluble as the union between the original States. There was no place for reconsideration, or revocation, except through revolution, or through consent of the States."