Anyone know what sort of platforms these systems run on today?
Apparently 80% of all bank transactions and 95% of all ATM transactions in America are still running COBOL, as is the Social Security Administration and DoD's finance systems (https://www.youtube.com/watch?v=TBs7HXI76yU)
x86 / VSphere ESXi / Windows 2016-19
Uptime requirements did not change. There was just a very strong desire to ditch the mainframes ... and a long and painful way there.