Sometimes technologies are saved by emulation within a new technology. For instance, the software for a legacy PDP-11 micro computer emulator can still be run in a browser. Others get taken up as hobbies. "Plenty of people still know how to do calligraphy, raise carrier pigeons and practice semaphore," he said. 

In still other cases, technologies find the niche they are best suited for. Morse code, for instance, "is fantastic for bad, noisy situations," he said. Ham radios and military units still use it to communicate when other methods are impractical. Prisoners use it to tap on walls and pipes. "This is a format where you can communicate by blinking your eyes," he said. 

"It's almost as though in the process of dying out from widely adopted casual use, [the media] actually found a space for which it is uniquely suited. Many media do this -- they find a niche after their death that is actually a better fit," he said. 

Sometimes the idea driving the media is resurrected in a new form. 

He pointed to an 18th-century version of Photoshopping, called black mirrors, or Claude Glass, which were tinted mirrors that transformed reflected images into painterly hues, giving the scenes a picturesque quality.