A more thorough explanation:

An expectant heir is a person who has a future interest in property or a chance of inheriting it. This means that they may inherit the property in the future, but it is not guaranteed. For example, if a person's parent owns a house and they are the only child, they may be an expectant heir to the property. However, if the parent decides to sell the house or leave it to someone else in their will, the child would not inherit it.

Another example of an expectant heir is a grandchild who may inherit from their grandparent's estate if their parent (the grandparent's child) dies before the grandparent. In this case, the grandchild has a chance of inheriting, but it is not guaranteed.