It's not obsolete if it still does the job it was designed to do. I've written my share of FORTRAN, RPG, COBOL and who knows what else over the years. No idea if any of it is still running somewhere, but if so, great! There are plenty of tasks that need attention, without inventing silly make-work like replacing fully functional existing code.

Things are only obsolete if they can no longer perform their assigned function. COBOL does not fit that definition by any stretch of the imagination.

There are shops that develop new applications in COBOL today, and do an enormous amount of useful work. Just because it doesn't fit someone's idea of 'the latest and greatest' doesn't mean it's a bad idea to use it.