Most of us don't need a desktop. We could already make due with a browser, and a small cpu with just enough memory to run that browser.
Thanks to all these web applications you just don't need a desktop, or desktop software. I can name very few desktop applications I cant live without.
Give me a browser and I'll be just fine.
And then I won't need a super fast computer. How much do you really need to run a browser?
Of course I haven't got a clue if such a thing is possible, but I'm sure that if some smart guy puts his mind to it he'll get it done.
Or maybe it's a really stupid idea and I'm just jumping on the trendy "cloud computing".