I learned COBOL for fun a few years ago, seeing it through the eyes of a modern programmer. It's unique among programming languages. I found the syntax remarkably straightforward, after I got used to some of the underlying concepts it's predicated against. It's not a bad language, and I'm okay at it.
The language has possibilities. Especially when the human computer interface moves from keyboards to voice, which I see as inevitable. It would be amazing if you could do the kinds of complex programming tasks by voice that you see in Star Trek, and I think we're only a few years off. Here, COBOL is the only established language that makes sense. Well, barring some of the more recent additions. No such application exists for it, yet, but it certainly could, and probably should.
As far as the banks go, you have to understand business. If a system works properly and needs very little maintenance, there is no business case for replacing it. It's not like anyone runs websites with COBOL these days. Typically, it's the language of big iron mainframes. If the current group of COBOL programmers does die out, it makes sense to train new ones.
It's not an outlandish suggestion. We pay people to learn new things all the time, even programming languages.