I wouldn't be so sure. Microsoft has lots of technologies that they dropped, including VB6, COM+, DCOM, DAO, ADO, ActiveX, Silverlight, WPF, WinForms, XNA, IronRuby, IronPython and the list is probably much bigger. I couldn't help but mention the Iron languages. Microsoft halted development right after open-sourcing them. And now they are effectively dead. Well no, open-source never really dies and those projects are just waiting to be adopted - which is the great advantage of open-source. But we are talking about Microsoft and their interests here.

Is it that much of a stretch to say that Microsoft is obsoleting .NET? Given the moves in "modern Windows" and WinRT, with their focus on HTML5 and the revived interest in C++, plus killing Silverlight / WPF which was the hot new thing only 6 years ago, well, it doesn't look good.