@tychotithonus @robertatcara It was definitely taken seriously where I was at IBM, and a tremendous amount of necessary mitigation was involved to prevent as many problems as possible. After Y2K, the software developer in charge of the operation transferred to our team.
We prepared for years, rewriting operating systems from 32 to 64 bits, and testing thousands of apps for compatibility. I worked mainly on Solaris and SVR4 for Fujitsu. Nobody was sure something wouldn't bite us in the ass. There was definitely some luck involved. Good times.