Maybe 'const' can't be fixed without breaking existing source code?
I don't really have a problem with adding a new keyword for 'actually const', maybe calling it 'constexpr' means C++ people have wrong expectations though, dunno.
For me, having constexpr being explicit about only accepting actual constant expressions, and creating an error otherwise (instead of silently falling back to a 'runtime expression') is fine, but the existing keyword 'const' has an entirely different meaning, there's just an unfortunate naming collision with other languages where const means 'compile time constant'.