Colin,
I think most of the assets were sold off 1-2 years ago possibly more - but an ongoing question remains about ownership of some of the models (donated / loaned / etc) and something popped up a few days back in a news-feed but did not catch what was said.
I think the best advice is to have paperwork setting out the condition of the donation or loan and who (or whose estate) the item should be returned to.
From what I understand Museums consider any item donated their property to do so as they wish (donate, sell, pass on to other museums..) unless there is a stipulation in the agreement. Even when selling a museum may choose to do so privately (direct to a dealer generally) to avoid auction fees. Recovery of the asset becomes difficult at this point.