Yeah, if you're looking for employment opportunities today, or in the next couple of years, learn C.
That said, if you want to be a better C programmer (and you already know C): learn and write Rust, and figure out what sorts of things you can't write in Rust and why. Once you learn how to make the Rust compiler's safety checks pass without it yelling at you all the time, you'll know how to write good code in a similar language without the safety checks.
I really like rust, and I think it's worth learning, but it is definitely in the early adopter stage and not something that has really made a dent in the embedded industry, let alone taken over.