For every
point in the past and present of
music, there is a corresponding point in the
future where even those most knowledgeable about music would stop being able to tell what was and was not. That is, no matter how much we know about the
history of
music and the current
directions it's moving in, there will be a time when they listen to sounds that are
meaningless to our ears.
To wit: A nobleman of four hundred years ago, if presented with experimental jazz of the 60s, would most likely be unable to identify it as being music. To ancient Plains Africans who had developed intricate, communicative rhythm to an art, the simplest melody -- say, Twinkle, Twinkle, Little Star -- wouldn't be interpretable as music. To a turn-of-the-century concert band director, even today's best Black Metal would just be noise. If Glenn Miller was given some nice ill drum'n'bass to listen to in 1940, he would probably have compared it to the static on an AM radio. And so forth.
It's a fun gedanken experiment to try and figure out what could possibly make the future's music so radically different from ours. One of my guesses is that as people get better and better at temporal control, -- ie, making either their medium or their interpretation faster or slower as circumstances demand -- eventually that control will extend to music. There might be twenty-four hour long masterpieces that if listened to by us would sound like endless, droning chords and buzzes, but if listened to with appropriate temporal control, would be purely beautiful. Another direction might be towards non-linearity, with thousands of sound inputs being mixed together by an ensemble of musicians to create one coherent, fluid work. The beginnings of this can be seen in today's DJ'd dance music, but try to imagine it applied to Baroque symphonies, and/or the complete works of Elvis, whale song, etc.