Alex Soojung-Kim Pang and David Pescovitz say we need a better word.  There's even a blog about the end of cyberspace.

I'm not so sure.  I don't think we have a better word than cyberspace right now, with its "self-steered" meaning.  It's a great word for a collective mind that orders itself and reflects its influences.

Talking about cyberspace is difficult, because we are fundamentally ill-equipped to understand it.  Legal thinkers are prone to imagine the world mechanically, as a collection of configurations of structureless particles, pushed around by enslaved forces.  Communications law mavens will say confidently that nothing much has changed in twenty-five years, and the Baby Bells and cable companies talk of "customized video products” and "viewing experiences," but that is not the internet.  Because the internet is made up of computers, people often forget that it is a non-mechanical social world, full of patterns that have arisen from decentralized local behaviors.  It is a constantly shifting kaleidescope of energy and attention.  Like all complex adaptive systems, the internet is constantly in a state far from equilibrium.  It is changing and adapting, causing itself to find its own stable organizational patterns that will themselves change in time.

The internet is the “transcendent” medium described by Judge Dalzell in the CDA litigation, characterized by low barriers to entry and parity among speakers.  It is not like anything we have seen before; it is not like broadcast or a newspaper or a telephone network—none of which could be described as complex adaptive systems.  We need to take a more imaginative approach when thinking about it. More data will not help us, and mere Newtonian mechanical references (the pure syntax approach) cannot explain what it is.  A Newtonian might say, “You have a particle with mass, it’s acted on by forces, and there you are,” and the cable/telcos have a similar approach:  they say this is just another communications network characterized by access points and flows of data.

"Cyberspace" is a useful portmanteau term.  It carries the idea of not needing external direction, the notion of spaciousness, and the feeling of a group mind.  Someday it will be in vogue again, and I'll still be using it.