I'd disagree with you on the literature point. Sure, Hamlet's value wouldn't depreciate if it was found to have been written by someone else, but I suspect the

I'd disagree with you on the literature point. Sure, Hamlet's value wouldn't depreciate if it was found to have been written by someone else, but I suspect the value of the Mona Lisa wouldn't drop too much if we found out da Vinci didn't paint it either. Both works derive more value from their own fame than from that of their creators. However, I would also expect a lesser-known Shakespeare play (and there are many) to fall off the map if it turned out he didn't write it, in the same way a less-famous Rembrandt (for example) is only significant because it's a Rembrandt.