It's a question of perspective. If you're looking for a total control and great performances, nothing has superseded C. If what you want if a faster development and feature release cycles, many have.
I'm definitively not against C, and definitively not against JS. But C used to be the language for every purpose, and now it's JS. History repeating I guess...
I agree with you on the "low-level browser based" point, but the reach of JS is way broader than that.