I was under the impression that the "internet" -- the physical backbone that comprises it -- was designed to be resistant to service interruptions. That, like a fine spider's web, it could automatically "route around" portions that were damaged. Or in other words, that there really can't be a "switch" that "turns the whole thing off".
I could understand how the government might order the net's major service providers to "disconnect themselves" from the internet backbone, though it's unclear if a law giving the government the authority to do this exists (I wouldn't be surprised if some secretly-passed law exists to this effect).
But pull the plug on the whole shebang? Something tells me that is unlikely.
Then again, we could always go back to short-wave radios!