Nobody really knows. It depends on whether or not leakage occurs.

However, it does not really matter. You still have to transfer stuff to the latest medium. For example, cd's are beginning to be replaced by dvd's, which are pretty much backward-compatable today, but for how long?? But dvd's will have a very short history to write, as they are soon going to be replaced by high-density and multi-level dvd's. What's next? Maybe ultraviolet or xray or some other RF device with a very short wave length capability...

It will not do you any good to have a perfect quality cd if there is nothing to read it with.