> What happens when some of this old hardware breaks and it becomes not only impossible to find replacement parts but also impossible to fabricate new ones in house.

You get a modern Fortran compiler, you compile the old code for the new stuff and off you go. What am I missing?

> Eventually, like all languages, Fortran will die out as time goes on. So few people know it now that it is inevitable.

Like ALL languages? Ha, tell that to the COBOL programmers at the heart of some financial institutions mate. Heck, RPG is still supported on some IBM hardware.