I agree but there is hope
I sort of agree with the article: most people who buy a computer expect Windows on it. On the other hand, I think there is still hope.
Love them or hate them, one thing that Apple have done for us over the past few years is show people that a computer doesn't have to come with Windows. One of my friends, who is the most un-technical person you would ever meet decided a while back that she'd get an iBook to replace her ailing Asus laptop. Her criteria for choosing the iBook was that it looked great and stylish. She had no problem learning how to use the dock nor that the browser was no longer a blue E but a blue compass or that the mail app was no longer a yellow clock but a mail stamp (which somehow does make more sense). Granted, she did put the whole MS office suite on it rather than using iLife but she did need to exchange documents with other people and Neo/Open Office was not up to scratch at the time (it's now better but still behind). So if she can switch OS, I think everybody can.
As for Linux, I agree that it needs to be a bit more polished in places but Canonical are doing exactly what needs to be done with Ubuntu. You can now use Linux without ever dropping to the command line and with everything working out of the box on a large variety of hardware. But most people won't ever get to installing an OS anyway, they'll use whatever is shipped with the computer, whether the hardware is well supported or not. A company that would start offering computers with Linux pre-installed and were to make the OS a feature of the computer, in the same way that Apple did, highlighting the difference rather than hiding it, would do well I think.