I guess that's a good point. I admit haven't used or seen `dynamic` in so long that I completely forgot about it.
But I'm not sure that's really a problem. Does the OP expect everyone to use an entirely different languages every single context? I have web applications and desktop applications that interact with Office that share common code.
Even `dynamic` is pretty nice as far as weird dynamic language features are concerned.
Interestingly enough `.ConfigureAwait(bool)` is entirely the opposite of `dynamic` -- it's not a language feature at all but instead a library call. I could argue that might instead be better as a keyword.