For everyone flabbergasted by Southwest running ~Windows 3.1~ old software, I have bad news about the telecom industry. I worked at Ericsson at an R&D branch and one of the projects in the works was to move one of the main pieces of routing equipment that handled millions of telephony operatorations a day away from an ancient version of Windows.
A lot of code lives on much longer than you think. The general attitude we took was that most of the code we were writing would be running for at least 30 years. And that was the attitude at an R&D branch, arguably a side of that industry where we were working on the new tech.
Edit: Win 3.1 or something else, the point still stands. There is a lot of old software running out there that will continue to run our core services. Legacy software doesn't just mean v1 versus v2, it can mean v1 versus v41.
A lot of code lives on much longer than you think. The general attitude we took was that most of the code we were writing would be running for at least 30 years. And that was the attitude at an R&D branch, arguably a side of that industry where we were working on the new tech.
Edit: Win 3.1 or something else, the point still stands. There is a lot of old software running out there that will continue to run our core services. Legacy software doesn't just mean v1 versus v2, it can mean v1 versus v41.