There's no pressing reason for a company to toss its legacy mainframes. What VP would sign off on replacing core systems that run an international corporation? The downsides are infinite! I mean, are you insane? Just throw money at an "expensive" COBOL programmer and get out of my office!
I grilled an employee at a Major Package Shipping Company a few years ago about their infrastructure, and it's pretty stereotypical: a few mainframes that were coded decades ago in COBOL and an expensive team of legacy programmers performing surgical tweaks. They're porting unimportant side systems to modern hardware + languages (ostensibly so the mainframe programmers can focus on the major systems), but there are no plans to replace the core. Ever. Replacement systems just aren't good enough to consider switching the heart of their company. And so it will continue until there's a compelling storyline for dropping mainframes
I grilled an employee at a Major Package Shipping Company a few years ago about their infrastructure, and it's pretty stereotypical: a few mainframes that were coded decades ago in COBOL and an expensive team of legacy programmers performing surgical tweaks. They're porting unimportant side systems to modern hardware + languages (ostensibly so the mainframe programmers can focus on the major systems), but there are no plans to replace the core. Ever. Replacement systems just aren't good enough to consider switching the heart of their company. And so it will continue until there's a compelling storyline for dropping mainframes