MDG, as mentioned above, a Jew always have heirs. If there are no children, you go generation up to children of person’s father and check brothers, then children of grandfather – uncles, then grand-uncles. Thus, everyone has heirs unless someone in the chain is a ger. Then, I believe the property becomes hefker and whoever grabs it, has it. In the case of Hashmonaim, they are kohanim, so there are no gerim there.
Maybe Cohanim now can join together and claim to themselves the ruins of everything Herod built.