That is an excellent question, one I should investigate using a VM clone one of these days. The accounting data is frozen in time, so it should not be affected, but if the system starts refusing logons or just crashing, that would not be great (and I'm pretty sure the SCO licensing management thingy would fall over, as that was a previous source of, eh, entertainment).

The plan is definitely to retire the system Real Soon Now, but with the subjects of the underlying data springing new generations with new lawyers, ensuring some kind of Y2K38 compliance might be wise...