> Is C++ going away soon? Or is it holding steady and even growing? How can someone objectively know either way?

No. It's not going away anytime soon, but you can look at high-performance languages that are gaining in popularity, and that may point to change in the future. TIOBE isn't perfect, but it's a good indicator of interest, and Rust and Go seem to continue to gain popularity.

Interestingly, and related to this article, Fortran has moved up from #31 to #20 on TIOBE's index, which really does speak to the importance of a math-optimized, high performance, compiled language. Another interesting change is MATLAB moving up from #20 to #14.