These corporations may not see it, because they do not understand it, but having such legacy systems a risk to their operations. The longer they wait to migrate, the more expensive it will be, and the harder it will be to attract talent to the project. There may come a point where they can no longer find anyone to support their hardware or software, and it'll force them to stagnate against their competition who may be able to provide better or different offerings because they are not tied to a system they can't modify.
My understanding of business is that you should never stagnate, and always keep advancing.
People that I've talked to who have worked with such systems indicated that they built giant shims around the systems in other languages to allow them to be adaptable. In theory this gives them a clear interface definition (it may be huge, thousands of method signatures, and possible direct schema access, but it can still be a clear interface) to boot strap a core system replacement in another language and hardware system.
My understanding of business is that you should never stagnate, and always keep advancing.
People that I've talked to who have worked with such systems indicated that they built giant shims around the systems in other languages to allow them to be adaptable. In theory this gives them a clear interface definition (it may be huge, thousands of method signatures, and possible direct schema access, but it can still be a clear interface) to boot strap a core system replacement in another language and hardware system.