Last year I had the privilege to learn about the IBM mainframe, and the mainframers converted me. It is one of the most advanced systems I have ever seen. IBM solved most cloud-issues 30 years ago, and the backwards compatibility is insane. Everyone is worried about 'code from the eighties' still running, but this just proves that the system is reliable. And in this datacenter (that I was learning about) the mainframe did 80% of calculations while only using 8% of the datacenter's power, because the machine is so terrifyingly efficient.

This is not just about converting COBOL code. This is about converting the JCL (batch processing) jobs to whatever cool real-time processing solution the new architecture is going to have, and about translating the security boundaries from RACF to new security controls. Using AI to 'convert' it might prove difficult, because I don't think we have the datasets to train an AI to do this properly.