IBM makes a lot of money selling mainframes to companies that have COBOL codebases dating back to the 70s or earlier. The main reason said companies still buy mainframes to run said COBOL programs is because it’s too risky to try to port them to more standardized, cheaper platforms. THEORETICALLY, a COBOL-proficient Claude could make it feasible to port these old COBOL codebases to something more modern that can run on bog-standard x86 servers, and it’s unlikely customers would buy them from IBM.

IF, and it’s a big if, Claude make it possible to migrate off of COBOL, this would be a massive blow to IBM.