This can be a very costly issue for large operations. Many facilities do not have the real estate within their computer data centers to support two fully operational systems. This can add to the challenge for implementing your Y2K solution. In the case where you manufacture a time related product, you must also have all the testing and certification completed long before the actual Y2K problem date. This is necessary to insure that you have time to release and distribute your product so that others may meet their Y2K compliance schedules.
Early release is essential to avoid both legal and operational support issues.
Having your product ready for release in December 1999 just isn't practical today. This page gives a surface only view of what the Y2K engineer is faced with. If it isn't, you're way behind and you will need to catch up quickly. Many companies have been working this issue for many years already. Mission critical data and systems must remain operational beyond the year 2000 and for every day after for at least another 100 years.