I assume you are talking about enhancing C# itself, because Roslyn is the next big thing for C# (and VB.Net) with a compiler compiler rewrite that will allow anyone to build language services.
The C# compiler code base is old now. It was done in C++ and apparently has become very hard to maintain. The C# team has been working on Roslyn, a complete rewrite of the compiler in C#, to make adding new features to the language more easily. It will also allow improvements to tooling (anyone can use the same compiler service rather than create their own) and should certainly facilitate meta-programming, construction of DSLs, etc.
I agree with you about F# though. It's so much to-the-point than C#, which is already a big improvement on java and C++ in the terseness area.
I love C# but I wish I was at least as proficient in F#, I know I could be a lot more productive with a language that requires less 'ceremony'.