This older article by Paul Graham talks about some interesting things happening right now.
Hardware becoming virtually exchangeable and disposable, data becoming device-independent, etc. Google with the cloud service machine and the whole tablet movement is steering right into this. And most important: ordinary users not having to know how and when to install or upgrade anything, or what "DSS" or "ZIP" means. They just need to tap a button to make it happen.
With Web-based software, most users won't have to think about anything except the applications they use. All the messy, changing stuff will be sitting on a server somewhere, maintained by the kind of people who are good at that kind of thing. And so you won't ordinarily need a computer, per se, to use software. All you'll need will be something with a keyboard, a screen, and a Web browser. Maybe it will have wireless Internet access. Maybe it will also be your cell phone. Whatever it is, it will be consumer electronics: something that costs about $200, and that people choose mostly based on how the case looks. You'll pay more for Internet services than you do for the hardware, just as you do now with telephones.
See, that's a tablet, in two or three years.