guess I am somewhere in-between....
There are some systems that will shut down, if not fixed......most will just screw up and make life miserable. The key to it all is the impact analysis, which if not done properly, is worse than not doing anything.
A while back a consultant from NZ tried to convince me to get into monitoring the consultants for the companies to ensure that they had systems in place that would ensure a 'quality' impact analysis...the dollars he sited were in the millions for 2 years work. BUT I chickened out, it was way over my head.....he didn't think so, but I did. I helped him get his consulting company system ready, and we prepared an ISO type presentation for him to present to his potential clients. It was fun, it has been very profitable for him (he is getting his millions)...he is a programmer, and now has 50+ people working for him on this project. he says teh little prep work we did has made the transition from a handfull of employees to what he has (now, worldwide)an easy task.
Anyway....I learned a bundle about the Y2K stuff from him.
The issues are in how much control the computer has on your manufacturing systems..automation, data transfer. MRP, ...financial issues are the worst....anything that triggers on a date....interest, payouts, life insurance, birth (age)....delivery dates, archived files
Problem is some programs have hidden dates....And you are at the mercy of your suppliers.....did they do it correctly? there are some people doing a "fix" and leaving the company with a false sence of security....and have in actuality done nothing. And there are systems out there that are still selling (sale prices...), that are not compliant.
Anyway.....i expect messy at best.