If there was any doubt about Fibre Optics eventually replacing coax and twisted pair phone lines and network cabling, that doubt has been crushed by a German experiment that sent 26 terabits of data through 50 km of fibre optic cable in a single second. Read about it here:
http://www.dailymail.co.uk/sciencetech/ ... ECOND.html
Other articles estimate that those "data rates" would allow a single piece of optical fibre to carry 400 million simultaneous telephone conversations.