I worked on a Y2K project in 98-99 for a major car manufacturer. They tested the ERP system for Y2K (in 1997) and it failed, in a way that would make the business fail. They replaced it via this project and the business continued to be successful without interruption.
Another company I know of simply backdated their whole system by 10 years. This worked, but unfortunately the contract cycle renegotation reminders then did not appear, and competitors took many of their contracts over the next year or so. They went out of business in a couple of years.
I implemented a new manufacturing and retail system in 1992, and we used 4 digit years. The company owner complained that they were a needless expense and annoyance and that there was plenty of time to deal with Y2K. They continued to use the system well into the 2000s.
The space shuttle never flew over New Year's eve/day as they couldn't handle a single year rollover, let alone a century. Some use cases can simply avoid the problem.