BUENOS AIRES—The point of the recent Congress of the Communist Party of Cuba, we had been led to believe, was to rejuvenate and modernize the structures of the state—even though the 15-member Politburo elected during the gathering is dominated by septuagenarians and octogenarians who have been rejuvenating and modernizing Cuba for 52 years.

The real purpose was to maintain the way in which power is allocated. The Castro brothers, ever the cunning tacticians, are ready to make concessions in many areas. But not on the definitive issue: the monopoly of power.

One need only look at the Politburo to see that Cuba is not an ideological dictatorship but a purely military one. Raul Castro, who now succeeds his brother as first secretary, has traditionally been the chief of the armed forces. The small clique of old guard members who have been “elected” to the Politburo have proved their loyalty during decades of collaboration with him in the military. The second secretary, Jose Ramon Machado Ventura, as well as the likes of Ramiro Valdes and Abelardo Colome Ibarra, are charged with preventing cracks in the barracks, not with forging the socialist “new man.”

The fact that all these men called to inject new life into the system are aging revolutionaries who have been with the Castros since the beginning is not the most farcical aspect of the party congress. That would be the assertion by Raul Castro, during a two-and-a-half-hour charade, that “the country lacks a reserve of well-prepared substitutes,” meaning that he and his clique will deign to serve a bit longer before they can cede power to a new generation. And how long, might one ask, will it take for a well-prepared generation to be allowed to emerge? Ten years, according to Castro, who seemed dead serious when he proposed that party leaders only serve two five-year terms. This should give him enough time to come up with a new proposal, just before he turns 90 in 2021, to prolong the rule of his old guard for a wee bit longer.

He was not entirely wrong about the lack of preparation. The reason there is no new generation in the party is . . . well, the Castro brothers’ habit of applying the political guillotine to younger figures. Carlos Lage, the former secretary of the Council of Ministers, and Felipe Perez Roque, the former foreign minister—two young “apparatchiks” seen, until a few years ago, as spearheads of an up-and-coming leadership—were purged as soon they stuck their heads out. And how exactly could a new generation become “prepared” when the Castros let 14 years elapse between party congresses?

Raul Castro, a greater admirer of the Chinese way than his brother, has launched what he calls “the updating of the socialist model.” He wants private enterprises to absorb about 50 percent of the island’s workers as part of a plan to eliminate half a million state jobs now and another half million later. Government-owned companies will enjoy more “autonomy,” and local governments will control more of their budgets. Self-employment will be allowed in a total of 178 activities.

The aim is to sustain the political bureaucracy by raising the productive capacity of the country. In its current state, and with Venezuela’s subsidies to the island under constant threat due to that country’s productive stagnation, Cuba risks social and political stirrings. There have been signs of this in recent years with various groups gaining some notoriety—and paying a heavy price.

But Castro’s reforms are insufficient for any major economic leap to take place. Rigoberto Diaz, a correspondent in Havana, recently interviewed a number of Cubans who have tried to start businesses under the new rules. The case of Elia Pastrana, who resigned from her government job, owns a fast-food stand and has one employee in Artemisa, about 40 kilometers south of Havana, is typical. She is having to close her business because the cost of the license, income and payroll taxes, and pension does not allow her to make enough to sustain herself.

Fidel Castro’s presence during the congress should be enough to put a stop to speculation about how much Raul wants to deviate from his brother’s orthodoxy. Fidel said it all when he summed up the purpose of the party session: “To preserve socialism.” Both Castros are in total agreement about this.