Unless secession is a certainty, I think what happened after Stalin’s death would be a good example to consider. I don’t know that piece of history very well, but I think several guys went off to the Gulags or disappeared. Having a tight relationship with the head of the KGB probably helped.
After Stalin died in March 1953 there was a power struggle with Khrushchev on one side and Beria. Other then Beria being arrested and killed allegedly in December. Some of the higher ups were placed in lesser roles are became plant managers in Kazakhstan. Zhukov was out after The Great Patriotic War, back in for a few years after Stalin died than out again and retired. NONE OF THIS WAS AS BLOODY AS THE ‘30s PURGES.
Until Kruschev consolidated power as Premier, rule after Stalin was by a small group of those left at the top who managed to outlive the bastard. Took several years and Nikita’s secret (for a short while) speech to the Party Congress denouncing him before the post-Stalin regime was consolidated. There was no heir apparent (Stalin had systematically killed off any possible successors throughout his long reign) and Levranti Beria, a genuine monster who ran the KGB during Stalin’s last years, was the first holdover to be “liquidated”. It’s difficult to predict what will happen when Kim III shuffles off his massive coil. Very different set of players and situation.