C still has it's place. It's not glamorous, but it works. COBOL has no decent replacements. Yet. Some have tried. Almost all have failed. Old does not mean useless. If it works, then it's not wrong.
I see mostly imaginary. As a back end systems guy for over 20 years, I deal with guys all the time wanting to introduce new tools into the mix that add zero value. There is a reason why *nix tools are still around. There is nothing that Python can do better than awk for grabbing data columns and piping them into some other tool.
There is a reason why COBOL still exists, for example, what with its ability to ensure accuracy out to 38 digits. Nothing else comes close w/o tons of extra crap libraries, questionable code mangling, and TRUST. Banks trust COBOL because it has an almost 60-year history of trust.
When kids get all shiny-eyed over golang or Rust or any other "new" language or tool and think it would be a good fit in the financial arena, I start to get a little nervous.
From my admittedly cursory look at D, I find nothing persuasive enough to get me to take it on and learn it when the chances of my ever using it are slim. I guess I'm just old school. It seems that every week there is a new language, framework, etc., and most of them are really not doing anything radically different. As a back end guy, I see most of the churn happens in the web dev world. I prefer old, stable, and very little churn, hence my continued love for COBOL in particular. I also like C++ and Python, but there is something fantastic about COBOL, sh, and awk, which are oft-used. I'm getting less and less enthusiastic about systems stuff now that I'm getting older and more into writing useful tools to help my guys. Call it an easy exit...
Nothing wrong with the languages you mentioned; they do what they do best. COBOL and Fortran are both fantastic and nothing yet truly replaces them. COBOL is accurate out to 38 digits, which is amazing for such an "old" language. Banks still like their COBOL and it just works. No stupid "libraries and/or frameworks of the month" to worry about, it compiles cleanly and every time, and it's easy to write and maintain. Modern doesn't always mean best. I still write tons of stuff in sh. If it's under 100 lines, it's shell, awk, or similar. COBOL and Fortran still have tons of life left in them. Every time someone undertakes a massive project to replace COBOL in the financial sector (usually driven by a latte-sipping hipster and his recently graduated ilk), it goes pear shaped. We still use hammers. They work.