The disruption is not about whether the paradigm is old or new. The fact is - today if you are building a small app and need some form of real-time features, your best bet is Node.js. Right from etherpad lite to socket.io you have the tools you need to be up and running and to support a few thousand concurrent users out of the box.

Of course, scaling it past that will be a problem with Node being single threaded and so on - but I believe that these are problems that Node.js will eventually address.