I think the issue here is that people working in fintech don't seem to come across these systems much, if at all - if you know one specifically, please tell us.
LVL3 is pure cobol. It has been recently deprecated but there are many banks who own the code and are still self hosting it, along with it's IBM green screen support.
Vision is a java front end in front of an updated cobol backend. When your reputation is based on your reliability and long term code stability, at what point do you risk making the conversion, versus training new developers to work on your system.
https://www.linkedin.com/jobs/view/business-analyst-afs-visi...
[0] https://www.theregister.com/2022/04/11/gds_gets_over_histori...
If the cobol is still there, it’s not due to risk. If anything, the cobol is a much higher operational risk than replacing it.
But it's very abstracted, part of our main product offering WAS abstracting it. On top of our ready to use applications, we offered APIs for higher-level data retrieval and manipulation. Under the hood, that orchestrates mainframe calls.
But even then that there could be more level of abstractions. Not every bank used screen-level mainframe access. Some used off the shelf mainframe abstractors like JxChange (yes, there's a market for this).
Fintech would be even more abstracted, I imagine. At that point you can only interact with the mainframe a few levels up, but it's still there. Out of sight.