Military intervention offers chance for peaceful transition
For every dictator who does not die in office, there eventually comes a point of no return - some unpredictable moment when one's iron grip on power evaporates overnight.
Robert Mugabe has just passed that point.
The immediate question now seems to be how his retirement will be managed.
There is immense respect for Robert Mugabe inside Zanu-PF, and officials in the ruling party say the military will try to handle things with "dignity".
He may be sent into exile, or allowed to continue as a figure-head president with little real power.
The next question is how the international community will react.
The African Union has a hardline policy of opposing the military coups that were once common across the continent, and as late as yesterday evening, the received wisdom among diplomats, analysts, and Zimbabwean businessmen was that the military wouldn't even dare take things into its own hands.
Zimbabwe is landlocked, and in such a fragile state economically that a blockade by South Africa, Zambia, and other neighbours could theoretically bring a junta to its knees in days.
For all their aversion to military interventions, Zimbabwe's neighbours have been increasingly worried by the country's ongoing economic collapse and the looming prospect of a messy transition when Mr Mugabe dies or retires.
If the current military intervention does not descend into violence, it provides an opportunity for a relatively peaceful transition.
It also installs a man - Emmerson Mnangagwa - who is well known to the political establishments in South Africa and Zambia, but also Britain, the former colonial power, and China, an increasingly influential player in Zimbabwe's economy.
No government will risk endorsing what is in effect a military seizure of power.
But as long as General Constantine Chiwenga maintains a veneer of constitutional respectability - by not declaring himself president, avoiding bloodshed, and allowing Mr Mugabe to retire quietly - don't expect the international community to kick up much of a fuss.
It may be just the solution many were secretly hoping for.