To this technically-aware (but not exactly extremely IT-savvy) person, it seems to me that the concept of a "thin client" computer using Google is like going back in time to the times of mainframe/minicomputer terminals where we all use individual clients to access the functions on the main computer.
Of course the connection speeds differ and we are dealing with different types of networks, but still it sounds more like "back to the future". And I found one IT article that says essentially the same things:
http://www.cnet.com/4520-6033_1-5759958-1.html
What if you had to buy software for your cell phone, boot it each time you turn it on, install applications, update software, and then try and use it daily. Since the answer is no, you just want to use the cell phone, you probably don't know that the software in the cell phone is updated transparently by the network, without you doing anything. What you want to do and all you care about is the phone works.
So the modern thin client is a bigger cell phone that connects to the net and has a browser as it's main application ... all most people really need, or want. The rest of the software you want to use, it's available on line from many suppliers. Store your files on a USB thumb-drive or on line. You subscribe to what you want.
Techies will still buy PCs, but the vast majority of people who just want to use the Internet will buy IMHO thin clients, ie the Internet cell phone. An ideal situation for developing countries. Gonna happen, as net speeds go up, it's going to be sooner rather than later. Too much hassle for the average Joe in keeping their PC running, the less technically savvy, the more likely the customer. Probably be nothing more than a swap out for your current cable box -- or a version of this.
I have DirecTV tivo, it works just like this, all it needs is a display to be a fully functioning Internet terminal.