Many applications will break, as will many operating systems and PC hardware. It is time to start thinking about how this will affect you. For example, my computers all support 4 digit dates in hardware, but unusual things sometimes happen. DIR commands only give 2-digit dates, so any program that uses their date field is likely to malfunction. QuattroPro 6.0 cannot handle years beyond 1999 as far as I can tell.
Assumption is the mother of all screw-ups.
We picked Valerio's for dinner because we liked the menu. Talking to the other diners, who sounded American, we learned that Tom Peters had recommended the place partly because of these cutesy sayings. IBM is a major sponsor of the Australian Open, the first leg of the Tennis Grand Slam. The reason they use DOS for all these networked PCS is to shorten boot time to almost nil. They assume that the machines will frequently be unplugged or powered down by tennis fans or maintenance people, not individuals likely to do a proper shutdown.