Essentially, the constitution grants the federal government a limited set of powers. Anything outside of that scope cannot be regulated at the federal level.

Historically, most laws have been written under the authority granted to Congress to regulate interstate commerce, as Wickard v. Filburn ruled that that that authority was to be interperated very broadly.

In practice, if Filburn is overturned, it would probably he replaced with a still broad reading to avoid the absolute chaos that a complete reversal would cause.