Most people in our recent debate over the future of Windows 8 thought that the operating system could be saved. I'm sure many people in 1491 thought that the Earth was flat, too.

The very day the debate came to an end, this headline appeared: IDC: Global PC shipments plunge in worst drop in a generation . Sure, a lot of that was due to the growth of tablets and smartphones and the rise of the cloud, but Windows 8 gets to take a lot of the blame too. After all, the debate wasn't whether or not Windows 8 was any good. It's not. The debate was over whether it could be saved.

Indeed even Microsoft defenders are no longer talking about Windows 8 in terms of a stand-alone project but instead they're spinning it as Windows 8 being "more like a living organism , made partly from familiar bits that have evolved over the last two decades, with several new strands of DNA tossed in. It’s due to be updated for more often, and it’s part of a much larger hardware-apps-services ecosystem that is also changing quickly."

Please. Changing too fast for the user-base was what turned many former Windows fans into Windows 8 haters. Some people think I've put too much emphasis on Windows 8's dismal Metro interface for why Windows 8 has failed. I don't think so. This isn't a matter of judging a book by its cover; the user interface (UI) is everything for computer users. If the UI alienates users, you lose them. It's as simple as that.

My comrade pointed out that I declared Vista dead six years ago, but that the Aero interface, which I like, started there. True, but that wasn't the point. I was right. Vista did die. Microsoft had to bring back XP to stop users from fleeing to Linux on netbooks.

Read this Microsoft's Windows 8 approach: Bold, arrogant, or both? Microsoft has done many bold things in Windows 8. No one in their right mind would accuse this release of being timid or overly cautious. But plenty of perfectly sane critics have attacked Microsoft for being arrogant, stubborn, and dismissive of legitimate complaints. They might be right. Read More

Now, Microsoft could revive Windows 7 sales, or make Aero Windows 8.x's interface, but from everything we can see about Windows 8.1, aka Blue, that's not what they're doing. Instead, Microsoft seems to be doubling down on Metro .

Idiots.

You think the least they could do is give users a choice between a real Aero interface and Metro, but no, they won't do that. I don't know what it is, but lately, UI "experts" seem to want to create interfaces that only appeal to their builders and not to any of their users. It's not just Microsoft with Aero. In Linux, GNOME made similar blunders with its 3.x line and many former Ubuntu Linux users think Canonical went on the wrong track with Unity .

Yes, we are entering a post-PC world. Tablets and smartphones are becoming more important... to sales. PCs are no more going to go away than mainframes did. We're still going to be using them in offices and homes for the foreseeable future. They let us easily do things that we need to do every day that we can't easily do with a tablet or a phone.

Perhaps most of our computing will move to the cloud , but you know what device we'll still be using for most of our interactions? It will be a PC, simply because it's easier to enter data with a real keyboard than any other interface.

True, it would be great if you could use one operating system for your PC, tablet, and smartphone. Besides Microsoft with Windows 8.x, Canonical with Ubuntu , Mozilla with Firefox OS , and Google with Android/Chrome are all making similar bets.

But I don't think that's essential. I think Microsoft could continue to dominate the important, but no longer growing, desktop market for years, even decades to come. However, I don't think they will.

It looks like Microsoft is betting all its chips on the silly notion that Metro will be the one true interface for its entire PC and device line. There's only one little problem with this idea. Sorry, but I have to say it again, look at the numbers: Metro-interface operating systems have already failed.

Fewer people than with any previous edition of Windows want Windows 8 . Vista actually looks successful when you compare it to Windows 8! As for tablets and smartphones, I think my ComputerWorld colleague Preston Gralla summed it up nicely in his analysis of ABI Research's report on 2013's tablet market: "Windows tablets don't even rate a blip in the $64 billion tablet market."

So, what do the numbers show? Not what do you want them to show, and not what would your faith in Microsoft would have you believe, but what do they actually add up to? The sum is that Microsoft is failing to hold on to the desktop market and that it has no impact whatsoever on smartphones and tablets.

Windows 8 may not just be a failure in and of itself. Unless Microsoft changes course, this may be the end of the Windows domination period in end-using computing. Indeed, some major financial firms, such as Goldman Sachs and Kleiner Perkins Caufield & Byers (KPCB), already believe that Windows has crested and that it's all downhill from here.

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