I don't expect the Moon Treaty to last forever. But the problem Mrs. Lang and anybody else who "bought" extraterrestrial property faces is that lifting the restrictions doesn't mean that their claims will be recognized as valid. I know I'll get into trouble for saying this, but the problem is the curse of private enterprise: Multiple competing "agencies" selling deeds, some of which may overlap; a situation guaranteed to end up in court and make lawyers very, very, rich. Kind of like having multiple, competing, County Assessor's offices each maintaining their own set of property maps. Some things only work when there's a single authority. I confidently predict that none of those pretty little certificates will be honored, and extraterrestrial property will end up being "owned" by whoever can get there and hold it. That's the traditional human way.