Narcissists are capable of change, though it may require changes in their environment as well as associates dedicated to making change possible. It is important to keep in mind that the individual's issues are beyond their diagnosis, and no two cases of narcissistic personality disorder can be approached similarly.
Narcissists do not become narcissists without any external factors. Narcissists typically come from an environment that encourages them to hide personal vulnerabilities and put on a false face to impress others. Narcissists cannot change until they realize their current environment is a safe space for exhibiting vulnerability, and that those around them will not think less of them as a person for doing so.