It's not the point I'm trying to make. Yes you can do fancy stuff like that and de-mainframing COBOL is to run in on k8s is the path I would personally choose if I had to deal with it. It sounds like a lot of fun and the sense of accomplishment to finally have it running should be great.

The problem is -- it's very smart and unique, while organizations that have this kind of a problem don't want to depend on unique set of skills of a few highly capable individuals. Everything needs to be boring and people have to be replaceable.

In this paradigm, vendor java with aws lock-in is a cost, but in-house fancy stuff with cobol on k4s done by smart people in house is worse -- it's a risk.