Many articles have been written about the end of Windows or Apple, etc, and they never come to pass. The latest naysaying, Windows is doomed on The Week gets it wrong.
There are core products a company relies on, and there are the products that are there to support the core products.
Microsoft Windows was created for Office, to provide a platform to protect it if (and when, in the 90s) Apple declined.
Microsoft Windows was never a core Microsoft product. It was made to run their core products (Office) back when a declining Apple could bring down Microsoft with it.
In that light, it does not really matter if Windows is beyond saving or not. What does matter is that Microsoft has platforms to run it's core software, and today it does: Android, iOS, MacOS, Linux are all available. And Microsoft is already diversifying it's platforms.