I see no reason to think that parish registers, censuses, BMDs, wills, military records etc will go, so we will still have the basic data. However, there does seem to be a real risk that some less official data may be lost - data which would help 'put flesh on the bones' of our ancestors (and us, for future generations).
On a flippant note - the sooner my old medical, employment and financial records are destroyed, the happier I will be!

Philip