The world will remember Venezuelan President Hugo Chávez’s speech on Thursday evening as the moment when he announced that he’s being treated for cancer. For Venezuelans, though, the speech was almost as notable for another reason: Perhaps for the first time in 12 years of increasingly personalist rule, we heard the president reading, actually reading, from a prepared text. And that, for a leader who’s elevated the extemporaneous rant into a kind of governing philosophy, was startling in itself.

The speech—weirdly formal, occasionally stilted, coming from a man visibly straining to hold back tears—was a puzzling end to a remarkable disappearing act. Up until his address, Chávez had vanished from public view for an unprecedented three weeks, unleashing a tsunami of speculation that had already badly destabilized his own government. Yet if Thursday’s speech was aimed at quelling speculation, it was certainly badly misjudged: Entirely devoid of medical detail and delivered in a style that was palpably not Chávez’s own, it felt as though it had been delivered by an uncannily talented body double. Far from putting an end to the rampant speculation that’s taken over Venezuela’s public sphere in recent weeks, the performance seems likely to push Venezuela down the road of dangerous destabilization.

The trouble is that elections are not scheduled for another 18 months, and in one way or another Chavista operatives will have to keep control of the country until then. Yet everyone in Venezuela—Chavista or not—can see that “Chavismo without Chávez” is not a stable proposition. When a government is as dominated by a single charismatic leader as Venezuela’s has been, a serious illness is coterminous with a stability crisis.

A comparison with Cuba is instructive here. Over five decades in power, Fidel Castro managed to institutionalize communist dictatorship enough to keep the country stable even through his protracted illness in 2007-2009. During that time, his brother was able to step into the breach with nary a peep of dissent.

Venezuela’s much younger hard-left experiment, by contrast, has shallower institutional roots. Venezuelans have been telling pollsters for years that they like their president but despise his ministers. Compared to the all-encompassing political machine that is the Communist Party of Cuba, Chávez’s United Socialist Party of Venezuela (PSUV) is weak indeed: a loose confederation of civilian and military factional leaders brought together, under Chávez, mostly as part of the hunt for petrostate spoils.