Yeah - I can tell you as a C# developer, I get contacted on Linked in several times a week. I'm not looking at all. And if they look at my history, they can see I've been at my current job just 6 weeks. That doesn't slow them down.
As mentioned above, enterprise solutions are huge. There's a lot of money there, and they rely on Microsoft solutions. Sharepoint 2010 has hooks into Dynamics CRM (accounting and CRM), data workflow and reporting (SSIS/SSRS), etc. I've only seen glimpses of 2013, and I think it'll be slow to catch on (as is typical in the corporate cycle) but it will likely be huge in the future.
As a .NET/C# developer, I couldn't disagree more with what the author is saying... So much so, that I really don't think he/she even knows what .NET is.
Maybe the author has the feeling it is dying because other platforms are in the news more often?