The author chides Googles for having two OS's with overlapping marketshare, yet seems to forget about WinCE, XP, XP Embedded, Vista. There is certainly more than a bit of overlap there.
And of course, like every other upcoming version of Windows for the last 15+ years, this next version (Windows 7) is going to be the end-all OS, with all the bugs and issues and whatnot worked out. We heard that about Windows 95, and 98 and 2000 and XP and Vista, yet it never really seems to hold true.
I personally think Google has a really solid shot at this. Microsoft just doesn't get it, their overhead is too large to allow them to charge a fair price for the product and still turn a profit. Apple is their own island and (IMO) doesn't really want or need to be a threat to the computing world at large, they target a successful and profitable niche. Linux is just too disjointed to ever become mainstream, that ship has sailed. But Google, they have the R&D power, the marketing savvy and the ability to create a universal OS that could directly challenge the Windows franchise, and I think the world is ready for it.
Google has developed so much of their own technology already, that an OS is probably not a major departure for them.