Yet another the sky is falling article about Microsoft from Forbes. The author misses some key things because the article is 100% client-centric - Windows isn't the predominant player on the client because people are buying tablets, so Microsoft is doomed, without realizing Microsoft basically owns the backend and is making a strong play to be the leader in hosting services and platforms in "the cloud" where all of those devices connect to do the things they do. So yes, PC sales are falling because people want smaller devices with better battery life, and while this may be the slow decline of Windows' dominance as we once knew it on the desktop (as an employee I hope not, but the market will exert it's will no matter what I personally want), I certainly don't think Microsoft is going anywhere but continuously upward on the backend/server side, and Azure is already a big player in "cloud" and getting bigger.
The article is correct without being accurate, in my opinion, but I don't expect much more from Forbes than article trolling for hits. It seems bashing Microsoft (erroneously) is the way they want to get some of their web hits, and they're using data to manipulate and match a story that's not exactly right. It's accurate, as far as the numbers go if you look at them how you want, but if you look at them showing what they actually represent, it's not quite right.
Also, for full disclosure, the author should have noted that all of the "Links" at the bottom of the page go to his own blog, so he's mostly using his own blog posts as the source for his article. It's just another log on the fire, for what it's worth.