No, it's not. For a clear example of that, take a look at how the so-called
"Income Tax Cases" were distinguished almost to irrelevance during the 18 years or so from the time those cases were decided until the time the 16th Amendment was ratified - time and again, the Supreme Court found one reason or another why a whole slew of different taxes weren't the sort of direct tax that the
Income Tax Cases had forbidden, even when they more or less were.
More broadly, however, no broad federal power long exercised stands or falls on a single case.
Wickard may have represented the nadir (if you will) of respect for constitutional limitations (to-date) on the Commerce Clause, but that doesn't mean that all contemporary understandings of the breadth of the Commerce Clause power stand or fall on
Wickard. For example, assuming
Wickard were repudiated on its facts by the Supreme Court, all of the jurisprudence regarding the instrumentalities and channels of interstate commerce - such as OTR trucking on the highways of the various states - still stands. For some faint allusions to this, see
United States v. Lopez, 514 U.S. 549 (1995).
I am not saying that there are favorable odds on
Wickard being overturned, or even substantially repudiated; however, I am saying that it is not beyond the realm of possibility. Do not forget that, until 1954, it seemed highly unlikely that the Supreme Court would ever repudiate the case of
Plessy v. Ferguson, 163 U.S. 537 (1896), and the doctrine of "Separate but Equal" based on that case, until it did exactly that in
Brown v. Board of Education of Topeka, 347 U.S. 483 (1954).
I understand that. That's why I specifically made reference to the Congressional "finding" of "substantial effects". There were other cases around the same time that laid some of the groundwork, and Wickard tends to be the lightning rod. What needs to be challenged and overturned is the "substantial effects" doctrine in general.
One of the most prescient pieces of writing I've ever seen on the subject, in my opinion, comes from Joseph Story's Commentaries on the Constitution
"The question comes to this, whether a power, exclusively for the regulation of commerce, is a power for the regulation of manufactures? The statement of such a question would seem to involve its own answer. Can a power, granted for one purpose, be transferred to another? If it can, where is the limitation in the constitution? Are not commerce and manufactures as distinct, as commerce and agriculture? If they are, how can a power to regulate one arise from a power to regulate the other? It is true, that commerce and manufactures are, or may be, intimately connected with each other. A regulation of one may injuriously or beneficially affect the other. But that is not the point in controversy. It is, whether congress has a right to regulate that, which is not committed to it, under a power, which is committed to it, simply because there is, or may be an intimate connexion between the powers. If this were admitted, the enumeration of the powers of congress would be wholly unnecessary and nugatory. Agriculture, colonies, capital, machinery, the wages of labour, the profits of stock, the rents of land, the punctual performance of contracts, and the diffusion of knowledge would all be within the scope of the power; for all of them bear an intimate relation to commerce. The result would be, that the powers of congress would embrace the widest extent of legislative functions, to the utter demolition of all constitutional boundaries between the state and national governments. "