Ideally, the narcissist would be self aware enough to know what their disorder does to make them incapable of real love relationships/attachments and avoid them altogether by learning to "self-supply" their need for fuel and validation from external sources. Think of it as aa predator who decides that becoming a vegetarian might be better all around. I don't think the majority of narcissists are capable of such self-awareness or self-control since parts of their brain do not work the same as a neaurotypical brain and their ego has been disabled to the point it is non-existent. There is a small minority of narcissists who can do this and are keenly aware, so this is hopeful. Perhaps there will be something in the future that will be a compensatory device (maybe AI) that can restore memory, brain function, and all impaired parts in them.

No one wants them to kill themselves, so that is never the answer. If everyone is educated to recognize these disordered predators when they meet them, they can still conduct business with them and even fratranize with them with one caveat. They would NEVER attempt to have an intimate reciprocal reality based relationship with them. They would establish boundaries and safety to protect themselves, stay in groups, approach with caution. If they understoog that these unfortunate trauma victims are disabled and incapable of humanity as we know it, they would protect their hearts and stop trying to love them back to wellness or fix them. They would treat them as any disabled mentally ill person, with compassion but caution.