You could run a stripped-down Linux distro on a Raspberry Pi without issue. Office automation apps might not work exceptionally well, but it’s something.
I don’t believe this hype, really. The Linux community is growing every day. This author seems to be focused solely on the user experience on Windows 8, which I agree is horrible, but he offers little in the way of legitimate market realizations for PCs to go the way of the dodo.
The BIGGEST reason we might see PCs start to dwindle is the idea of cloud-based thin clients or virtual desktop infrastructure (i.e. VMware VDI) where we all have stripped-down desktop PCs running on remote kernels. We already use them in the business world. I don’t see it being a big seller in the consumer retail market though.
A remote kernel, with local storage, would be interesting. No need to worry about viruses, since there is no local OS to infect, but your data could still be fairly secure residing physically on your own computer