Personally, I don't consider myself an Angular developer - I'm a developer (a "full-stack developer" if I had to qualify the term somehow). I can pick up any Javascript framework in a reasonably short amount of time, because I have a lot of experience with the language.
Furthermore, who's to say you'll still be using Framework X a year from now? Your needs will change, and all of a sudden the premium you paid for that specialized talent is money wasted. Just hire talented developers - they'll learn whatever stack you throw at them, every time.