An acquaintance, a decade ago, took about 5y off to go on a world tour. When he returned to London, his skills were so stale, he couldn't find anything.
After 6mth of hunting in vain, he wrote a CV focussed on his oldest skill -- Fortran -- and found a role in weeks. When he told me this, he'd been renewed 5 times and had been in a 6mth role for nearly 3 years. He suspected he'd be doing it for the rest of his working life.
I got a bunch of interviews around 2010-2011 for DEC OpenVMS sysadmin work. I do have VMS skills, but not high-level ones -- but companies were having real problems finding people to maintain their Alpha and Itanium servers. The demand was there.
Yes, COBOL is still being used at many of these companies, but other departments are using up-to-date .NET or Java and don't ever look at COBOL.