For at least a decade, there's been talk of the balkanisation of the Internet and, to be honest, it seems that no one has done anything to prevent it. I'm talking about the possibility of a country going beyond Internet censorship and literally closing itself off completely. Iran will probably be the first to finally do it. After that, who knows which countries will follow.
Most governments do not like the free and open Internet because it causes problems with authority. For one thing, all the riots over the film insulting Islam prove that some populaces cannot deal with the Internet.
Much of the Internet is censored here and abroad anyway. Most corporations run their connections through mechanised filtering services so employees cannot visit certain sites during the day. Cut out of the mix are scads of innocuous blogs and other useful sources of information. Nobody bats an eyelid in the UK or US. Do you think an Iranian sitting in an Internet cafe will care that much?
For one thing, the web is so big right now that you can easily cache a huge piece of it and have it available on the locked-down Sovereign Net within a country. You just cannot go outside your Intranet at all.
Some countries like China, Korea, and Saudi Arabia have tried to design a model in which filtering accomplishes this. Still, there are all sorts of VPN and proxy mechanisms that manage to bypass the scheme. If one person can escape the prison like that, then theoretically, everyone can do it and will do it. These Sovereign Nets have got to be completely closed off, but the problem is this will never happen. Some guy, usually from within the government, will have an outside connection. That's all it takes.
The Internet is interesting because it is insidious. Do you even know for certain that your machine is not providing a neighbour with a connection somehow? Are you part of a bot network? Is your machine sending out spam at night? Why are you leaving the machine on when you are not using it?
If Iran, or any other country for that matter, is going to shut itself off from the Internet, then it has to shut itself off completely with no leaks or backdoors. This also means the phone system has to be locked down so mobile users cannot tweet or visit Facebook unless a locked-down version of that code base can be installed within the Sovereign Net.
The way I see it, Iran or any other embargoed country is given the go-ahead to steal source code and put up Facebook-Iran. How are you going to sue them for copyright violations?
This is not a political point regarding Iran or North Korea. What I'm saying here is that it is very difficult to keep the Internet out. Even the stupid censoring is ludicrous and a waste of time and money. Censoring the web is like using an airgun to rid the backyard of flies. It's a joke.
That said, killing the web altogether and setting up a local rinky-dink system would only work if the rulers of the country also cut themselves off, which they will never do. Regardless, I'm predicting that a number of countries will attempt to pull off this stunt and fail miserably. You cannot easily put this genie back in the bottle, but someone will try.