The problem with that is, this would affect companies outside of the US as well. As long as nameservers are hosted here in the States, the USA will have the power to shut down any site, worldwide. Even if the nameservers are moved, the US would still have the power to block all US citizens from accessing the sites. Don't pretend that won't have a profound influence on the world.

Maybe a worldwide blackout would discourage other governments from attempting something similar.