I support a VB.NET web app with dynamic page generation (as opposed to controls on a control surface, and a second C#.NET web app with the control surface page generation.
.NET is still the king of web app development.
No doubt, .NET Framework was built specifically to support web apps and services.
.NET (or .NYET :) has never been the top choice for web app development, since it's tied to Windows. Linux and Unix power most of the big sites, with Java providing the horsepower for "enterprise class" development.
Java has been the #1 language in terms of jobs for quite a while.
Here's a chart from an analysis of 45,000 job postings on Twitter for the last 12 months:
From: http://www.sitepoint.com/best-programming-language-learn-2014/
Back on topic, I think Swift looks pretty darned good. I hope open source implementations are allowed.