The world was treated on Sunday to an amazing sight: thousands of Cubans taking to the streets in a wave of demonstrations demanding, among other things, an end to a 62-year-old dictatorship.

Beyond serving as a milestone moment for the island nation, the demonstrations in at least 15 cities marked the latest installment in the greatest struggle of our times: the contest between democrats and authoritarians. In recent years, authoritarians often have seemed to hold the upper hand. Yet the Cuban unrest serves to frame the key question: whether authoritarian regimes will prevail in the long term, or are sowing the seeds of their own demise.

The Cubans who took to the streets appeared to have some more immediate concerns on their minds. They were protesting a lack of food and a shortage of Covid-19 vaccines. But their willingness to take their protests to the actual doorstep of Cuba’s Communist Party headquarters showed a deeper dissatisfaction.

It’s hard to say whether Cubans on the streets, like citizens of Hong Kong pushing back against Chinese central government repression there, represent the beginnings of a new anti-authoritarian tide or mere footnotes in a generally bad time for those who cheer for democracy.

Certainly authoritarian regimes appear to be having a good run right now. Freedom House, a nonpartisan organization dedicated to promoting freedom and democracy, reports that freedom across the globe has declined for 15 straight years, a trend that accelerated last year. “The long democratic recession is deepening,” Freedom House says.

Across a swath of central Europe and central Asia in particular, a total of 18 countries suffered declines in democratic trends last year, while only six in those regions saw improvement.

Videos show thousands of Cubans protesting food and medicine shortages and calling for the end of dictatorship, in a rare show of dissent. An uptick in coronavirus cases and a slow vaccine rollout are adding to the island’s worst economic crisis in decades. Photo: Stringer/Reuters The Wall Street Journal Interactive Edition

Those trend lines, and the staying power of authoritarian rulers, are apparent among the world leaders who pose the greatest challenges to the U.S. and the Biden administration. In Iran, Ayatollah Ali Khamenei has been the country’s supreme leader for 32 years, triple the time that Iran’s revolutionary leader, Ayatollah Ruhollah Khomeini, held the post. This year, he stage-managed an election that put his chosen candidate into the presidency, and who is likely on track to become the next supreme leader when Mr. Khamenei dies.

In Russia, Vladimir Putin has been in power, as president or prime minister, for 22 years, longer than the seemingly immovable Leonid Brezhnev ran the Soviet Union. Mr. Putin is moving up on Joseph Stalin, who ruled for 29 years, and is well positioned to pass him in longevity, considering that he has rearranged Russian law so that he can stay in power for more than another decade.

In China, President Xi Jinping has been running the show for a mere nine years, yet he has developed a cult of personality and engineered a removal of term limits, thereby allowing him to become ruler for life. Turkey’s president, Recep Tayyip Erdogan, and Venezuelan President Nicolás Maduro seem no less intent on squelching any threats to their personal power.

So this seems a boom time for autocrats. Yet the seething unhappiness in Cuba, Venezuela, Iran and Hong Kong, and the need for Mr. Putin to poison and jail his opponents, raises the question of how long the authoritarian run can last. Is it possible that embedded autocracies create the conditions for their own eventual downfall?

Democracy is messy, but in an authoritarian system the problem is the lack of messiness. Cults of personality develop, opposing voices with potentially good ideas are squelched, healthy debates and innovative thoughts are blocked. In a new piece in Foreign Affairs magazine, China expert Jude Blanchette notes this risk for Mr. Xi in China: “Paeans to the greatness of ‘Xi Jinping Thought’ may strike outsiders as merely curious or even comical, but they have a genuinely deleterious effect on the quality of decision-making and information flows within the (Communist) party.”

At least China has done a good job of managing its economy. Elsewhere, authoritarian systems have produced a plundering of national resources, corruption and a general mismanagement of the economy.

“In the long term, you would expect autocrats to pay the price,” says Michael Abramowitz, president of Freedom House. “The problem is, the long run can be a very long time.”

He notes that today’s autocrats are more politically savvy and attuned to meeting material needs when necessary to blunt calls for civil liberties. And, of course, authoritarians can operate in a more closed information environment.

So, yes, maybe autocrats lay the groundwork for their own demise. But they also may be getting better at being autocrats. Meanwhile, democracy’s best offense—especially in the U.S., leader of the free world—is simply to make democracy work better so it is more easily seen as the superior alternative.

Write to Gerald F. Seib at jerry.seib@wsj.com