So, as we narrowed down the possibilities, let me try it once more, with speculations going full steam ahead.
2, Its unlikely that Anders will invent a new language like Dart/CoffeeScript.
3, Simply put MSIL2JS there is not optimal, so its more about tooling.
So, as Roslyn has a scripting API, with fully dynamic REPL support, maybe we will see a Roslyn based client-side web development environment, provides Edit&Refresh dev experience, using C#/VB or C#Script(csx)/VBScript(vbx) as the development language, MSIL2JS as compiler backend, TypeProvider-like dynamic integration of data sources and Web API, Razor-like HTML mixing, etc. Now the question is, does it support XAML ?????
So, Steve Lucco for the runtime (Chakra), Erik Meijer for the bridge (MSIL2JS), Anders for the language and tooling (Roslyn), three pillars of something ?
OK, as Charles said, its all about fun, but there is definetely more fun for hits than misses, so lets wait and see, 20 days to go.