Windows remains 800lb gorilla on the desktop, and C# is Microsoft's recommended environment on it. It's hardly surprising that .NET remains relevant.
It's a great time to be a .NET developer.
I'm not one bit surprised this is the the guy leading the C# effort's second or third language.
Even popularity is a value, as it automatically provides a community, but it's also a pitfall, as massive popularity inevitably means the average programmer of language X becomes as smart, careful and reliable as the average programmer irrespective of language. And, to put it mildly, that's not a positive evolution. That, above all others, was VB and Delphi's downfall.
On three axes, I would argue VB, Javascript and Delphi did/do incredibly well: ease of development (of small-ish programs), and the deployment story, as well as the empowerment they provided.
On things like consistency, developer productivity, batteries included (Delphi was better on the batteries included front), type system soundness, ... they were somewhat sub-par.
It's just what people value at the time. And of course, it is critical during a career in development to distinguish yourself from the average programmer.
In the short-term, languages with good developer outreach and other factors win. But you don't get things like generics or the .NET TPL without some serious long-term vision. I really do believe well-designed languages win over a long enough timescale.
I'm not necessarily saying it would have failed, but I do wonder :: )
Sure, the language being nicely designed and having some code translation tools helped people switch from VB.
But C# being the “best supported” language in Visual Studio. The productivity gains for developers were too real to ignore, managers saw it, and bought into the Visual Studio ecosystem en masse.