Given that the Python foundation has been trying to get folks to run a python-to-python converter for more than a decade and have not completely succeeded, I'm

Given that the Python foundation has been trying to get folks to run a python-to-python converter for more than a decade and have not completely succeeded, I'm skeptical that an AST transformer is really sufficient for migrating off those legacy systems. More constructively, having worked on a (close to decade-long, by the time I joined) project to migrate a financial institution's business logic off an IBM mainframe onto more modern architecture, my main takeaway was that these systems have worked pretty darn well for decades with relatively little maintenance. The reluctance of companies to migrate god-knows-how-much data, business rules, and institutional knowledge (e.g. of data entry folks, business-level administrators who have to navigate these systems to do their job, etc) off a time-tested system they trust at massive expense, is completely understandable.