The big problem those guys are running into is that they aren't paying anywhere close to market rates for engineers working in more modern stacks. Senior developer pay tops out around $120k last I checked and they've been reliant on cheap offshore contractors for years now to insulate themselves from paying modern dev wages in the US.
Funny thing though, the contracting firms are now notifying these companies that they won't be supplying COBOL developers into the future because there's a lot more money to be made contracting out devs in modern stacks than COBOL. It doesn't get a ton of attention because nobody can see the future, but hearing my dad talk about his company makes me slightly concerned about the future of our digital payments infrastructure.