FORTRAN users beg to differ. The horse they backed will be here until the lights go out because it probably is used to power the lights at some level.
And a lot of it is embedding FORTRAN or COBOL in the new pretty C/++.
New skin, same system.
In Julia, too.
Whose permission do you seek who will "let you" or not "let you" write a critical system in some new relatively unknown language? What if you work for yourself or are creating a startup?
[1] I think it's spelled that way these days, but of course given the context of the thread, maybe you're talking about old-school FORTRAN.