Whilst the non-existent adoption amongst startups doesn't necessarily bode well for MSFT's future, there is still a huge amount of .NET development going on worldwide.
What fraction of that .NET jobs would you call "interesting" of "cutting edge"?
.NET developers aren't in the endangered species list. Not more than COBOL developers who know what CICS means.
If you read HN enough, you'll find that rbanffy's posts generally seem to come from a worldview where credit due to Microsoft, or even to those who use Microsoft products, is close to untenable. In other fora I've seen similar people referred to as ABMers - Anything But Microsoft. I mean, I'm pretty much a Linux/Unix guy (Macs and Linux alike), but I use .NET because it's the most portable option worth working with for my stuff. It's good for that. Sometimes even--gasp--Microsoft comes up with something worthwhile, and outside of the universes perpetuated by folks like rbanffy, many Microsoft products are even liked.
Only thing i really miss from pro is plugins, version control-integration and code contracts, the last being a thing that probably justifies a price tag anyway.
Now their WinForms ability might be great, but there are few start ups out there at are actually doing anything with desktop development.