Not a COBOL developer, but working at a sizeable bank I witnessed the phasing out of their mainframes and AS400 systems. They ran some critical systems, both in retail and wholesale banking. They either converted to java, and optimized that code, but some COBOL code from the mainframe, and all of the AS400 stuff was converted into Micro Focus COBOL, which runs on Windows, which could be hosted on our Private Cloud. I worked on helping them migrate to our cloud infra, which was an interesting exercise. There was a very tangible cultural gap between the people maintaining and developing these applications and the rest of the organization.