The key to overthrowing an unpopular autocracy is to puncture its image of invulnerability. Once that happens, the regime can crumble very quickly. One day, Assad is apparently in complete control of Syria; the next, he’s hiding in Moscow.
There is a lesson here for Xi and Putin. Of course, they already knew it. That’s why they fear “color revolutions” so intensely, and why they won’t tolerate even the smallest manifestation of opposition.