If the court says that the provisions of the GPL are invalid, that doesn't mean Vizio gets to just use the code
That is not on the table though.. It is more a question of What is the applicability and enforcement of the GPL, And who gets to enforce it, and what is the remedy. If it were just the authors of the software suing over GPL violation -- your remedy for breach of license would typically be money damages or Injunction - Pay us money; Plus cease and decist distributing the violative code. On the other hand "Release to us all additional source code you were obligated to have included as per the license agreement" would be an Equitable relief of specific performance -- extremely rare for courts to grant, unless it is part of some settlement agreement, and the judges would need the answer to the question - Why money and injunction alone are not enough to make the authors whole.
The GPL is a binding license agreement No doubt. What is extraordinary here is the party suing is not the copyright owner - they are suing on behalf of consumers. 3rd Party beneficiaries who are technically not parties to the license agreement.
The GPL is not between consumers and Vizio - it's between the authors of the software and Vizio.
So the courts could very well end up Dismissing the case making the determination that end consumers - the public in general does not get a remedy over the GPL violation, and only the authors of the software used are harmed, by having their copyright infringed. This is what you would expect. It will be an extraordinary earth-shattering thing if the court decides that the public and consumers in general have a remedy over GPL violations.
It makes sense, Because placing the code under the GPL is intended to be a gift to the public, so violating the terms is Unlawfully stealing not just from the author, but from the public ecosystem as well. On the other hand, courts have never acknowledge that as such with open source licenses before, And it is very possible they will end up not acknowledging it today.
But if the precedent is set that the public can sue over GPL violations, AND specific performance will be ordered (You must comply with the GPL by immediately distributing all witheld code. It is not that you can pay a few dollars to each class action member to settle the claims of a class.), then the GPL becomes much more powerful.