I. Prohibit Congress from regulating activity that occurs wholly within one State.My sense is that this is intended as a reinforcement of the limits of the Interstate Commerce Clause against SCOTUS overreach. As you know, a long series of SCOTUS rulings have expanded that power until it is essentially unlimited: it is now a power to regulate any economic activity that has any effect on commerce sufficient to plausibly affect interstate prices, but also power to regulate economic non-activity that might affect prices where the Federal government would like to require some activity (e.g., health insurance purchases you haven't been making).
Since states are forbidden to raise tariffs that would isolate their markets, the law of supply and demand means that any supplier in any state affects the market as a whole. The same is true for people who elect not to become suppliers. It is not clear what aspect of life is thus outside the expanded scope of Federal power under this revised understanding of the Interstate Commerce Clause. Presumably, the state can regulate any sort of economic production or non-production: you can be made to do or not do anything at all, and more than that, you can be told not just that you must do it but how to do it as well.
If this section has a weakness, it lies in the fact that the language does not specify that it is talking about "economic" activity. Presumably as written this would strip the Federal government from any power to regulate any sort of activity that occurs wholly within a state. On the other hand, the limiting force of the word "economic" is not clear to me: the Interstate Commerce Clause, which clearly is limited to economic activity, has somehow expanded to embrace any sort of activity or non-activity. It may be that there are very few human activities that cannot be described as economic.
I am going to propose a general standard for considering these amendments, which is that it is best if they start off stronger to leave room for negotiation in the necessary Constitutional convention. The amendments should be a little stronger than necessary going into the convention, so that what emerges from the convention is more likely to be adequate medicine.