I foresee only minor aggravation with PC software, and so far have been able to expeditiously handle the changes required. There is rarely a question, when dealing with actual data, of what century is involved. Minor data manipulation or macros have allowed me to wrestle the numbers into submission. This is accomplished with simple logic. There is no need to manually change millions of dates.
Computers are skilled enough to do that once the proper algorithm has been determined.
When it comes to the corporate world, the approach is typically to hire very expensive consultants and shovel lots of money at the problem. The solution can be complex in that some of the original coding of the earlier programs has been lost. This may be a good time to look at all the software to see what is truly useful, or necessary. While I was in the corporate realm, we kept getting buried under an increasing load of computer printouts. My boss would request periodically that the distribution of some report, which did not make sense to him, be discontinued.