This is interesting to me as I am a junior in college and I just got an internship where I will be dealing with a mainframe that uses COBOL. I'm really psyched about it as it seems like it will be interesting, but I wonder if because the skill set is disappearing the jobs that require that skill set will go along with it.
Perhaps it really is a good reason to upgrade if you can hire experienced Java programmers for half as much as experienced COBOL Programmers. (I'm only guessing on this from a supply and demand perspective.)
Businesses seem to have a mentality that if it works don't touch it. I get the impression that with mission critical application that isn't an attitude you can afford to have. Especially if there comes a day when it doesn't work and there is nobody around that knew how it worked in the first place.