It depends on the society I suppose.
—China: The CCP has an iron grip on the country. There is no serious challenge, democracy-based or otherwise, to its rule. If Xi Jinping were to keel over dead tomorrow then there is no doubt another senior CCP official would simply be slotted in his place.
—Russia: Might be rattled by Putin’s sudden death. To my knowledge it’s a rickety system based on cronyism and he’s the glue that kind of holds it together. There’s a real pro-democracy movement in the country. However, Putin’s death would create an unstable situation and it’s anyone’s guess how it would sort itself out. Like the aftermath of the Arab Spring, it’s possible Russia would be worse off. We can’t assume removing the dictator will heal the society — there are many examples that disprove that.
—America: Another interesting one. Trump has a firm grip on the GOP but it’s a minority (barely) party. However, Trumpism has now so thoroughly infected the GOP that it’s hard to imagine Trump’s death would really change its political trajectory. Mitt Romney and Jeb Bush won’t come roaring back. Rather, DeSantis, Cotton, Hawley, Cruz, MTG, and those radicals will inherit it. Trump dying might even make the GOP stronger since Trump is so politically toxic himself.