Google's official blog discussed cloud computing 10 years hence - far more eloquently than I did recently.
In a nutshell, most computing power will come from web-based services (effectively, Everything-as-a-Service), and our own computing resources will be mere devices that hang off the cloud. Not quite like the dumb terminals on mainframes of yore, though. They rightly see continued exponential growth in the three mainstays of power: processors, storage, and networking (the essential plumbing). Our devices will certainly be powerful - but not a shade on cloud resources. (I see the power in local devices being chiefly used to drive our interaction with the cloud, in the long run.)
They see a great plethora of devices hooked up, many of them far smaller and more specialised in application than our typical laptops/desktops.
They also dare to speculate on the smarts - intelligence - built into "the cloud". Read it all here.