There aren’t the votes. When the issue of medical marijuana came up, the Court voted 6-3 that a ban by Congress of even homegrown marijuana did not violate the commerce clause. The majority in that case was comprised of Scalia, Kennedy, Souter, Stevens, Breyer, and Ginsburg. All six of those justices remain on the Court. What that proved was that the four liberals on the Court were not willing to change their stance on federalism, even when it was something they were sympathetic to (medical marijuana). Since all six of those justices are still on the Court, there’s really no chance at all that the Court would strike down the PBA ban for federalism reasons.
Thanks again. I also just saw this from Justice Thomas’s concurrence via NRO: “I also note that whether the Act constitutes a permissible exercise of Congress’ power under the Commerce Clause is not before the Court. The parties did not raise or brief that issue; it is outside the question presented; and the lower courts did not address it.” Which is pretty much what you said before: the federalism issue was not in “play” here.