Understand completely.
Please note that I stated that my answer was conditioned as “ULTIMATELY.”
Nullification is a great historical principle to stand upon (and discuss), but if the Supreme Court decides something in contravention, an Amendment ratified by the 38 States is the final word. Even the Supreme Court would not (or I suppose, could not) try to overturn an Amendment. Or would it?
Jefferson:
In the wake of Marbury v Madison, Jefferson wrote, in a letter to Abigail Adams, "... the opinion which gives to the judges the right to decide what laws are constitutional, and what not, not only for themselves in their own sphere of action, but for the Legislature and Executive also, in their spheres, would make the judiciary a despotic branch." Simply put: if the Supreme Court has the power to say what is and is not constitutional, there is no limit to the court's power (and hence, to that of FedGov).