When iTunes and the iPod were launched together in 2003, they precipitated a revolution that transformed the music industry. It's hard to believe, sometimes, that it was just nine years ago.
Before then, the music industry was about access to physical objects: records. That's how it worked for Vera Lynn, Madonna and Britney Spears. At a stroke, iTunes dispensed with all that. No more records, no more global distribution network, no more record stores: instead, customers could simply download what they wanted, when they wanted it. It was a strange, and - for record company executives - frightening new world.
The industry is only just coming to terms with the disruption that Steve Jobs caused by persuading us to switch from ownership of physical copies to ownership of digital copies. But now, a new and even more radical shift is coming. It's the emergence of a world in which no one owns copies of music - or, indeed, films or books - at all. Instead, we simply dip into the information cloud that surrounds us, to listen, watch or read when we want.
Sitting on the train, and just remembered A-ha's Take on Me? No problem: reach into the cloud and it will be there. In this new world of streaming content, access to music is as easy as turning on a tap.
Take the streaming music service Spotify (www.spotify.com), which allows users access to its library of millions of tracks via a website, or, for paying customers, a mobile device. More than 23 million people used the service last month, and, if it meets its growth targets by 2014, Spotify will pay more in revenue to the major music companies - in short, will be a bigger deal in the music industry - than iTunes. Meanwhile, in the US, Netflix (www.netflix.com) saw its DVD rental business lose 2.7 million customers in the last quarter of 2011, while its online movie-streaming service gained 220,000 customers. And late last year, Amazon launched the book streaming Lending Library service on its Kindle reading device.
Driving all this are age-old consumer desires: for speed and convenience. And, of course, the connective, mobile technology that makes it all possible.
But it's the implications that are most important. For the generation now coming of age amid streaming content, the idea of a traditional, bespoke record or book collection - cherished, nurtured, stacked neatly on the shelves - will, surely, make no sense. In this new world, music and books are not things that we own in the traditional sense, as we own a car or pair of shoes. Rather, they're just there, all around us, for everyone to use. Music, publishing and film industries will never be the same again.
But there are far greater potential implications. Will the rise of streaming content lead to an overhaul in our consumer society's entire conception of ownership? Our current relationship with the objects we buy and use already looks increasingly archaic, given the rise of connectivity that makes possible new kinds of sharing and communal access. Why own a car, for example - which often sits in the driveway unused - when you might use a mobile app to "stream" yourself a car from a communal pool in minutes, wherever you are?
It can't be long before we start asking ourselves these questions en masse. And that means the streaming revolution could lead to far more than some empty shelf space.
David Mattin is a senior analyst at www.trendwatching.com.