And it's mainframe / COBOL, not DOS, which post-dates it by about a decade and a half.

It's not even an ASCII text app, but an EBCDIC one. Or was after EBCDIC was defined as a standard, after SABRE itself launched.

That is a tremendously fun fact! The little background things that keep society running. May I never be cursed enough I would ever have to directly work with such a system.

I wonder if it will ever go away.

It'll probably never go away, but just be layered over like civilizations. Eventually our software is probably going to get so complicated that we just build new software to interact with old software to avoid ever fully shutting it down. Like building a fresh highway on the oregon trail

Even if this incident is the proverbial straw that breaks the camel's back, the migration itself would be a multi-year project.

I don't think SABRE has anything to do with Southwest's outage.