[toyg]

I would expect this to be officially settled before the embargo is actually lifted. Ownership of nationalised industries and other US assets has always been item #2 on the diplomatic agenda, with #1 being military alliances (originally with the USSR, now Venezuela and China).

I expect the Cuban government will concede on a few national-level items (like legitimacy of the Guantanamo base) in exchange for the US government publicly affirming that any ownership claim from US businesses and individuals pre-revolution will be considered null and void. Anything else would be complete madness. Apart from difficulty in tracking original documents (which were likely destroyed during and after the revolution), handing nationalised assets to US citizens would mine the economic power base of the ruling elite in Cuba.

Consider hotels: they power one of the few sizeable economic activities on the island, i.e. tourism; but any hotel built before the revolution (and there are quite a few, all around the island) would have to revert to (likely US) previous owners, instantly transferring a lot of wealth out of the island. Not gonna happen.