GIVE the Castros of Cuba some credit. They are not as repulsive as the Kims of North Korea. They lock up fewer of their subjects, and the last time they terrified the world was in 1962, with the Soviet Union’s nukes. Both families have controlled communist dictatorships for decades (the Kims since 1948, the Castros since 1959). But at least the Castros are calling a halt to one-family rule—though not, of course, to one-party rule. This week Raúl Castro, the brother of Fidel Castro, who led the Cuban revolution, will hand the presidency to someone with a different surname.

This will be a big moment. Although Raúl Castro lacks the charisma of his late brother, he fought alongside him and succeeded him as president in 2006. With Raúl’s retirement, la generación histórica will give up day-to-day responsibility for governing (though he is expected to remain head of the Communist Party, the most powerful institution, until 2021). His probable heir, Vice-President Miguel Díaz-Canel, is nearly 30 years younger. If the change is merely one of generation and family there will be little to celebrate. Like the despotic Kims, Cuba’s regime keeps its citizens poor and unfree. Many Cubans will now look to the new president to change that.

Mr Díaz-Canel, an engineer by training, has sent mixed signals about whether he is a reformer or a reactionary. Whatever his instincts may be, he will be influenced by forces that pull in opposite directions. On the one hand, the economy needs to be unshackled if it is to provide Cubans with better living standards. On the other, the Communist Party is loth to give up control, or to allow the rise of an elite that might compete with it.

To Vietnam, and beyond

It has to do something. The economy is comatose. Venezuela, which subsidised Cuba after the Soviet Union no longer could, is itself imploding and has cut back support. The value of imports has dropped by a third since 2008. Cuba’s farms and factories produce little. Fuel shortages have led to blackouts. The state manages to feed and educate Cubans and provide security along with a basic level of health care, but little more than that.

Less photogenic but more flexible than his brother, Raúl allowed entrepreneurs to enter 201 trades, from hair-cutting to book-keeping. Some 580,000 Cubans, about 12% of the workforce, are “self-employed” in the liberated professions. They have lifted the economy, not least by catering to tourists flocking to the island. But Cuba’s rulers are frightened of these go-getters and of the inequality that will follow if they prosper. In August the government stopped issuing new licences to restaurants and hostelries, supposedly to fight tax evasion. In December it restricted licences to one activity per entrepreneur.

If Mr Díaz-Canel wants to preside over progress rather than stagnation and decline, he will have to liberalise further. The reform process has barely begun. An insane multiple exchange rate keeps unproductive state firms alive (by giving them almost-free money) while robbing exporters. Switching to a single, unrigged exchange rate would allow a more sensible allocation of resources. There would be costs: workers at state firms revealed to be unviable would lose their jobs. But private firms, if allowed to breathe, could hire them for work that actually adds value.

Optimists think Mr Díaz-Canel will guide Cuba towards the path taken by China and Vietnam, where communist parties liberalised the economy without yielding political control. The prosperity that would bring would be welcome. But people should not have to pay for it with their freedom. Though less repressive than it was, the government still restricts the media, intimidates critics and tolerates no opposition.

Cuba’s neighbours can encourage change but not compel it. America tried compulsion, by isolating Cuba for decades. It did not work. The Castros simply blamed America, rather than their own policies, for Cuba’s poverty. Barack Obama loosened the economic embargo, hoping that closer contacts would spur change. That made its leaders nervous. With Donald Trump, they are back in their comfort zone. He has partly reversed Mr Obama’s opening to please anti-Castro zealots in Florida. In Havana, America looks like a bully again. But Mr Trump is quite capable of shaking things up. He is soon to meet Mr Kim. Why not explore a deal with Mr Díaz-Canel?