Many banks and other financial institutions are finding this out now in their desperate bid to find competent COBOL programmers to continuing maintaining legacy critical applications running on mainframes when most COBOL programmers are retired or dead, and more are headed that way every day. It wouldn't shock me to find out that the effects of COVID being weighted towards worse outcomes for older people had a material effect on the human resource risk of using COBOL-based critical systems.
Banks will absolutely hold on to anything to avoid an unknown risk as long as they think they can hedge or mitigate known risks, and utterly fail to acknowledge the truth of unknown unknowns. This will ultimately be their downfall if governments ever let them follow standard business outcomes, otherwise they'll eventually absorb some upstart to keep hedging forever.
Nassim Taleb has written entire books on this fact about banks. It's interesting that the same flaws in their financial thinking apply to their IT infrastructure.