You're right that the Xbox is now profitable. (When I first googled this I came up with some links that suggested recent non-profitability, but I had misread the dates on them.) But at this point it still doesn't look to me like the kind of product line that can grow into something to sustain the Microsoft we are used to.
As for the critics, they missed what was obvious to me at the time. The main purpose of the Xbox was not initially to make money. Few remember now, but a decade ago Microsoft and Sony were butting heads in many different areas. (Particularly ones involving DRM, storage formats, and other things of interest for media providers.) In typical Microsoft fashion, they went after Sony's air supply. Competition from the Xbox forced Sony to slash prices on the playstation, which cut Sony's profits in half. This distracted Sony, which made them a less dangerous competitor in areas where Microsoft was going head to head with them.
(Of course in the end Apple did an end run about both by demonstrating with iTunes that you can deliver content without DRM and make everyone happy. Microsoft never sold the world on DRM everywhere, all the time. And Sony learned the hard way that people really don't like having a rootkit slipped on your computer without your permission...)
Now I grant you that Microsoft put a lot of energy into .Net, and it has achieved some success. But I look at that as more of a sustaining effort. Microsoft has always had programming tools aimed at certain sections of the business market. They have changed the tools, so what used to be done with VB and Access is now done with C# and SQL Server. But fundamentally it doesn't seem to me to be a radically new market, nor do I see much evidence that their market share has changed significantly.
As for Xbox and Bing, I absolutely agree with you that they are very similar stories. Just as Microsoft used the Xbox to try to neuter Sony, they are using Bing to try and undercut Google. It will be interesting to see how that goes. I think that Google's recent stock price is evidence that the market thinks there is a real threat.
However the bigger threat to Microsoft is coming from Apple. And Microsoft is nowhere to be seen in that space. Furthermore despite the threat to Google from Microsoft, there is more of a brain drain from Microsoft to Google than vice versa. And I see more entrepreneurs worrying about competing against Google's offerings than Microsoft.