If some madman who hates philosophy found a way to destroy all works of philosophy where-ever they exist in print or electronically stored so the only 'remembrances' of such work are 'with' a few experts what would happen to Philosophy or Philosophers?? If they 'started over' would they come up with the same lines of arguments as before?
In my opinion, all the most successful philosophy eventually disseminates into the larger culture to the point where it becomes inseparably and invisibly integrated with all the productions of that culture (novels, music, organizational structures, etc.). Therefore, destroying all the works of philosophy would not be enough to entirely destroy the philosophies contained in those works --although a great quantity of valuable ideas could certainly be lost that way.
I would go as far as to say that the biggest danger would be, perhaps, that it would immediately become much harder to counter any idea or ideology that was formulated in such a work, but that had already disseminated into the larger society.