A possibility of reverter preceded by a fee simple determinable, a right of entry preceded by a fee simple subject to a condition subsequent or an executory interest preceded by either a fee simple determinable or a fee simple subject to an executory limitation becomes invalid, and the preceding fee simple becomes a fee simple absolute, if the right to vest in possession of the possibility of reverter, right of entry or executory interest depends on an event or events affecting the use of real property and if the possibility of reverter, right of entry or executory interest does not actually vest in possession within thirty years after its creation.