Comment by gregjor

The big problems likely have very little to do with COBOL, which is just another programming language, not an alien artifact. The problem is legacy systems like this that pre-date relational databases (mid-1980s) have huge volumes of data stored in application-specific formats that modern languages don't have drop-in packages or libraries for. The data is always a bigger problem than the code in large systems.

For the record, I wrote enterprise software in COBOL back in the late 70s and early 80s. COBOL itself is no big deal to learn or read. Working with huge volumes of data stored in proprietary binary formats (which COBOL was designed for) is not something I want to go back to -- relational databases rule the world for a good reason.

As for shunting some work to another system, imagine how you would do that with something much simpler. Suppose Excel suddenly stopped working for you with some big spreadsheets. How would you shunt that to another application? How would you do it without risking the important data? It's not a simple problem of just spinning up more servers and replacing some old data management code with MySQL or Redis.