The poster said "music". Not "Cds", not "music recordings": Music.
If music no longer exists: it doesn't matter what capabilities the internet has for transmitting it --- it's gone. pfft.
It doesn't help us to have DVD players if no one's ever invented movies... Nor will it help us to have streaming broadcasts of television and radio on the internet if no one's ever invented either music or broadcasting.
There might be games: but they would have no background music whatsoever. You might have Napster: but there'd be no movies, tv shows or music on it.
What are you going to talk about on the internet without any other media? :P