Most adherents of the Dharma believe that the Buddha Nature cannot be destroyed. That is an error. All things are impermanent. The Buddha Nature is no exception. But impermanance is not destruction, but simply a change of state.
Yet I declare that the Dharma Nature will go on and the Buddha Nature will die? That requires explaining.
First you must understand the difference between the Dharma Nature and the Buddha Nature.
All living things have a Dharma Nature, including the human creature. This means that each living thing has its particular form of Dharma, which is subject to change over time through natural evolution.
That evolution is beneficial for the collective survival of the Life Force and while there is a natural extinction in progress the tendency is an increment in the potential individual survival.
Once the Life Force, in and of itself, is set in motion it is irreversible.
Evolution works through mutation. Mutations are genetic and occur in two ways: they can be inherited from a parent or acquired during a person’s lifetime. Mutations that are passed from parent to child are called hereditary mutations or germline mutations (because they are present in the egg and sperm cells). It is these mutations that set and develop new patterns and changes in life.
Almost all mutations which are not beneficial for survival fall away, but in the human creature one mutation became a virus. It was the evolution of language. That language gave the human creature an incredible biological advantage, but it provided the human creature with powers of abstraction that led to the belief in his individual existence and thus separated him from the mainstream of the Life Force. Identity was born.
But that Identity born in Cognition and stored in Memory had a balancing counterpart in the right hemisphere. That was the fount of the Buddha Nature.
That Buddha Nature set the paradigms for survival, which can be described as a drive for personal survival, a drive for Survival of Ofspring, a drive for the survival of tribal associations, and a drive for the survival of the animal and vegetal ambit which supports all life.
This set was mutually balanced, so that self-survival was not supreme, was developed within evolution and was the most advanced form of life.
But just as the Dharma Nature is impermanent so is the Buddha Nature.
Now changes in both Dharma Nature and Buddha Nature come about by the presence of behavior that is prevalent in the particular deme pool of each Life Force.
The Dharma Nature is uncontaminated, but the Buddha Nature is threatened. When gene changes take place in sufficient individuals in a deme pool and they reproduce, then there will be corresponding changes passed from generation to generation.
The probability that confusion or aversion become the dominant behavior in society is remote, but greed or acquisitiveness of the Identity is quite another matter.
We know that physiological changes take as little as seven generations, perhaps less. How long it takes for basic program changes is not known.
What is clear is that eventually the survival programs of the right hemisphere will be reduced to the personal survival paradigm. It will no longer be a Buddha Nature, but an Ego Survival Nature.
How far are we from that point? Perhaps very close.