I think someone has missed Windows Phone 7 and the tablets Microsoft will be releasing shortly. Hell, Microsoft Courier looked like the only tablet I wanted. Screw iPad, Courier was cool.
But the truth also is that Microsoft has a huge dominance on computer market and that isn't going anywhere. They are truly dominating it. I don't think it's a warning as such to Microsoft, just a suggestion for if they want to grow. And interestingly, that is what Microsoft is and has been doing for many years already. Xbox360 is a truly fantastic product too.
Just bring me something that Courier was supposed to be. I want it, I need it! Combine that with environment like Windows where everyone can freely develop their software and include things like XNA and Xbox Live and you have a wonderful product on your hands!