Indeed. If there is a market for COBOL programmers (and it's clear there is), then the obvious solution is for unis and colleges to spit out more COBOL-literate CS graduates. Honestly, if I was ten years younger, I'd probably delve into it myself. It is, after all, just a programming language, and hardly on the same level of trying to learn Sanskrit.
As long as you have a real fall-back so your career doesn't dead end. What can easily happen is that you do X then more of X because it's the only place you get a salary/career development until you've done X so long nobody will really hire you for anything else
Well, I guess it still depends a bit on whether you present yourself as a Java/C#/whatever programmer who's recently done some COBOL work, too, or as a COBOL programmer with a Java/etc background...
BTW, I started my career programming COBOL in an era when PCs began to replace mainframes (while the place where I was working was already a bit late there), and at first they used COBOL for writing PC applications, too, simply because most of their programmers didn't know anything else.