For originalists, a most difficult and pressing question is what to do about applying the First Amendment and other parts of the Bill of Rights against the states. That has been done heretofore via the Due Process Clause, but that type of incorporation has been widely (and rightly) regarded as illegitimate. If clearly illegitimate, those cases ought to be overturned, because deliberate usurpation of constitutional power is not nice, and is the most dangerous sort of precedent. But there are alternatives to simply letting states decide for themselves what to do about these fundamental rights.
The leading alternative has been to use the Privileges or Immunities Clause of the Fourteenth Amendment, but that Clause unfortunately makes the rest of the Fourteenth Amendment look like a model of crystalline clarity by comparison. While I have in the past supported a rather narrow interpretation of the Privileges or Immunities Clause that would only apply against states those rights that are spelled out in the Constitution, the arguments for various other interpretations of that clause are non-trivial and plentiful, so it's quite understandable that the courts have been reluctant to go along (cf. the 2010 case of McDonald v. Chicago in which the Privileges or Immunities Clause was the basis for the deciding vote of Justice Thomas, though I doubt it was because of the amicus brief that I wrote urging that approach).
If the First Amendment is not incorporated against the states, it would not be the end of the world. On the contrary, the country would doubtless pass a new constitutional amendment just like it has done plenty of times already. But there is no need for that, in my view, because Congress has ample power to get the job done. To keep things simple, I will focus here only on the speech and press clauses.
No one, presumably, would dispute that Congress has ample power under the Commerce Clause to say that no state shall infringe the speech and press rights described in the First Amendment, with respect to journalists traveling from out of state who are speaking or writing within the scope of their employment. The same is probably true even when opinion or news journalists from out of state are speaking or writing outside the scope of their employment, for at least two reasons: first, it is necessary and proper to avoid the difficulties of determining exactly what expression is inside or outside the scope of employment, and, second, journalism would be chilled if journalists despise visiting states where they cannot fully exercise such a fundamental right as free speech outside of their work. Suppose, then, that Congress backstops the freedom of speech and press for journalists by enacting such a statute under the Commerce Clause (I do not know whether President Trump would sign it after characterizing the mainstream media as an enemy of the American people, but suppose he does not veto it).
One might object on Comity Clause grounds that it is unconstitutional to discriminate between in-state and out-of-state journalists. Indeed, though “privileges and immunities” typically do not include natural rights, they can still refer to the means of protecting natural rights. But this is no problem, because the Comity Clause only requires that a state not discriminate against citizens from out of state, and does not prevent discrimination in favor of citizens from out of state. So the federal statute protecting journalists should withstand constitutional scrutiny (it also may be that the Comity Clause only refers to certain rights of all in-state citizens rather than just a subset like journalists).
Now, consider the Equal Protection Clause. Presumably most lawyers would agree that when a state inhibits the ability of everyone to speak and write freely, but makes an exception for journalists from out of state, that raises a reasonable equal protection issue. And, because speech and press rights are fundamental, strict scrutiny of the state’s discrimination ought to be triggered in the courts. In my view, then, the Equal Protection Clause can be used to extend the coverage beyond journalists, to everyone else in the state, including not just local journalists, but also bloggers, protesters, and all other human beings in the state. That is because the state does not have a compelling interest in protecting speech by out-of-state journalists alone.
Now, I would like to anticipate some objections. First of all, one might argue that the business of journalism can flourish even if reporters do nothing more than observe and then go back to their home states and report about it (by speaking and writing). While there is some truth to that, still Congress has always been allowed under the Commerce Clause to regulate commerce based upon moral and cultural concerns rather than economic concerns. That is evident, for example, from the Constitution itself, which explicitly allowed Congress to bar importation of slaves after the year 1808. And there is no question that securing the speech rights of itinerant journalists is a regulation of interstate commerce.
Another possible objection is that combining the Commerce Clause and the Equal Protection Clause in this way would not be limited by the Bill of Rights, and so would place unlimited power in federal hands. My response is that the power in federal hands would actually be reduced, because instead of the judiciary unilaterally decreeing fundamental rights based (improperly) upon the Due Process Clause of the Fourteenth Amendment, any such decree in the future would require a concurrence of Congress (in exercising the commerce power) with the judiciary (which determines how the Equal Protection Clause operates).
And how about the cases that have explicitly limited congressional power under the Commerce Clause, like U.S. v. Morrison which addressed sexual assault? Can Congress forbid sexual assault during any interstate business trip, and then have that law extended via the Equal Protection Clause to everyone else in a state? Well, no, because there is typically no state action when a person is sexually assaulted, whereas the Equal Protection Clause has always been understood correctly by the courts as a limit on state action only. Likewise, this concept of combining the Commerce Clause with the Equal Protection Clause to protect free expression would not commandeer states, because states would not be required to take any action for or against anyone; but, if a state tries to act against free speech by out-of-state journalists then the state would be stopped via the Commerce Clause, and if the state tries to act against free speech rights of anyone else, then the state would be stopped via the Equal Protection Clause. States are stopped right now from violating free speech rights, without any suggestion that a commandeering principle has been violated.
Let’s consider one last scenario. Suppose Congress purports to forbid people from smoking indoors in public, nationwide, on the basis that secondhand smoke would chill businessmen from visiting smoky states. First of all, I doubt that Congress would want to do this. Second, I doubt that the courts would deem freedom from secondhand smoke to be a fundamental right. Third, the Equal Protection Clause would not be applicable because there would be no state action. Fourth, the Commerce Clause would be an equally adequate (or inadequate) basis for such a federal law at virtually every public indoor place within a state, so the Equal Protection Clause would not be needed even if it were applicable.