My question is very general, but I'm not sure how to phrase it differently.
I'm thinking about the end of Apartheid in South Africa, the end of fascist regimes in Europe and Asia, and the end of communism in the USSR.
People who lived in those regimes and supported those ideologies, at least in their tacit acceptance of them, later lived in a world where they were no longer viable. I'm especially curious about the countries where ideologies were so radical and influential, such as the nationalistic movements in some countries. It seems that, in some cases, the same people maintained power while upholding, or seeming to uphold, different ideals.
Is there some predictable chain of events, or a generalized explanation? If not, can you provide information about the regimes I've mentioned above? I'm also interested in the politico-ideological state during the regime's decline.