That's exactly what we were told in 1996 (21 years ago that is) when I entered my engineering school: to disregard Cobol and Fortran, because, you know, OLD tech. Won't matter much longer.

If the cost of training peons to make it last and run is less than the cost of rebuilding it, be it from scratch or piece by piece, it will matter longer (that's the point of view of insurances, banks and big corps today, and what's still happening in the IT industry).