Keep in mind that when you choose ASP.NET you're only locking yourself to a platform, not a language. At my office, for example, we're looking forward to using F# -- by all means a well-designed, thoughtful language in the ML family -- to replace some particularly awkward and gunky C# code, and using F# won't require any more than a few tweaks to our build scripts and tools.

As for hiring: we've yet to hire a programmer who primarily worked in .NET before starting; good devs are language agnostic, and the people who built amazing software in Cocoa, Smalltalk, Lisps, and Ocaml prior help us build amazing software on .NET today.