I think he alluded to the coming of the Internet several times, but only in passing. His whole notion of a coming "global village" connected by an instantaneously accessible medium seems especially prescient in itself. Here's something he said about the "next medium":
"The next medium, whatever it is — it may be the extension of consciousness — will include television as its content, not as its environment, and will transform television into an art form.”
-Marshall McLuhan, ‘The Invisible Environment: The Future of an Erosion.’ Perspecta, Vol. 11 (1967) pp. 162–167. Published by the MIT Press.
"This externalization of our senses creates what de Chardin [sic] calls the "noosphere" or a technological brain for the world. Instead of tending towards a vast Alexandrian library the world has become a computer, an electronic brain, exactly as in an infantile piece of science fiction. And as our senses have gone outside us, Big Brother goes inside. So, unless aware of this dynamic, we shall at once move into a phase of panic terrors, exactly befitting a small world of tribal drums, total interdependence, and super-imposed co-existence."
“Our new electric technology that extends our senses and nerves in a global embrace has large implications for the future of language. Electric technology does not need words any more than the digital computer needs numbers. Electricity points the way to an extension of the process of consciousness itself, on a world scale, and without any verbalization whatever. Such a state of collective awareness may have been the preverbal condition of men. Language as the technology of human extension, whose powers of division and separation we know so well, may have been the “Tower of Babel” by which men sought to scale the highest heavens. Today computers hold out the promise of a means of instant translation of any code or language into any other code or language. The computer, in short, promises by technology a Pentecostal condition of universal understanding and unity. The next logical step would seem to be, not to translate, but to by-pass languages in favor of a general cosmic consciousness which might be very like the collective unconscious dreamt of by Bergson. The condition of “weightlessness,” that biologists say promises a physical immortality, may be paralleled by the condition of speechlessness that could confer a perpetuity of collective harmony and peace.” – Understanding Media (1964), p. 80, MIT Press ed.
“Instead of going out and buying a packaged book of which there have been five thousand copies printed, you will go to the telephone, describe your interests, your needs, your problems, and say you’re working on a history of Egyptian arithmetic … they say it will be right over. And they at once Xerox, with the help of computers from the libraries of the world, all the latest material just for you personally, not as something to be put out on a bookshelf. They send you the package as a direct personal service. This is where we’re heading under electronic information conditions.” (p. 101)