Narcissistic Collapse presents itself as a massive mental breakdown after which they become withdrawn and isolated. They struggle to face themselves, and as a result can’t face the world.
Narcissistic Collapse is generally permanent – the narcissist never recovers for the rest of their life.
There is a less common variant known as Narcissistic Hibernation. This generally happens when the Narcopath loses their key sources of narcissistic supply and therefore struggles to maintain their charade. They lie low until another is found and from whom they are able to derive sufficient narcissistic supply to feel good enough about themselves to face the world again.
This is the karma about which pundits offer refer. It’ll happen, sure enough. And if you as a victim want to accelerate the onset of narcissistic collapse, just go out there and thrive. Your success deals them hammer blows.