Nobody gives up power willingly, with very few exceptions. I would say that is not auth specific.(Ironically Stalin tried to step down multiple times, we can debate the authetisity of those times elsewhere.)

From a purely materialist pov, once we reach sustainable communism, the state is no longer required to manage material division. At that point, to be honest, I don't know. I would like to think that a state without purpose would simple wither, but I think we all know that is highly idealistic. So I'm going to cop out and say let's focus on getting there first.

I'm an optimist at heart. ( Think Che's quote on a revolutionary love) And I would want to believe that no one wants power if there is no reason material reason to pursue it. I also understand that is grossly naive and unrealistic. So how do we handle it... Man that's a hell of a question huh? If you find a good answer, let me know?

Che's quote I mentioned with context: https://www.quotescosmos.com/quotes/Che-Guevara-quote-23.html