But VPN usage can be detected and punished. China and Iran already do this. Bottom line is, if you've got the power and the will, you can definitely control the "how" and "what" of internet access in your jurisdiction.
But China and Iran are not democratic nations. And he has less than 2 years. If Iran has the power and will, and hoe come they have routinely fail to stop those sabotaging their infrastructure. I think China is the only one with that unique capability right now.
90% people don't know how to use VPN or too lazy to use it.