Who would control the power to regulate commerce in the US if this decision or a subsequent decision like it has not occurred? Explain

Article 1, Section 8, Clause 3 of the U. S. Constitution, which gives Congress the power "to regulate commerce with foreign nations, and among the several states, and with the Indian tribes."

I believe within its regulated in a much more local way, like states and then within towns and then cities, etc. This is my guess though for the "within" Part