Hours after learning her husband Alexei Navalny had probably died in a remote Russian penal colony, Yulia Navalnaya made an unplanned appearance at the Munich Security Conference to tell western leaders who she held responsible.

“If this is true, I want Putin and all of his entourage, Putin’s friends and his government to know they will be held accountable for what they have done to our country, to my family and to my husband. And that day will come very soon,” Navalnaya said.

Yet the death of the charismatic anti-corruption activist at 47, announced on Friday by prison authorities in the town of Kharp in the Arctic Circle, means the “beautiful Russia of the future” Navalny often spoke of as an ideal has never looked so distant.

Vladimir Putin is set to extend his two-decade rule until at least 2030 in presidential elections next month. His few serious challengers are either dead, in prison or have been barred from running.

As his invasion of Ukraine draws closer to its second anniversary next week, Putin has never looked closer to victory, with western aid for Ukraine flagging and Russia’s forces making slow but steady progress on the battlefield.

And his two, very different main rivals — Navalny and the late warlord Yevgeny Prigozhin — are both dead. The Kremlin has been widely accused of involvement in both fatalities.

“Putin isn’t supposed to have any competition. But he [did]. Not so much in the electoral sense, but the existential one,” said Andrei Kolesnikov, a Moscow-based senior fellow at the Carnegie Endowment for International Peace. “Now our commander-in-chief doesn’t have any competition.”

The deaths of Prigozhin last year and now Navalny have “just deepened the autocrat’s loneliness on Mount Olympus”, Kolesnikov added. “His power isn’t just safe, it’s absolute.”

Fiona Hill, a former official on the US National Security Council, said: “This is just [Putin] saying: ‘It’s just me, guys. You’d better get used to it.’”

The death must “terrify” Ukrainian president Volodymyr Zelenskyy, said Hill. “[Putin] is saying: ‘I don’t care who I kill and how many people I kill. I’ll get whatever I want.’”

In Moscow, dozens of people lined up to lay flowers at the Solovetsky Stone, a memorial to Soviet political prisoners outside the headquarters of the FSB security service, the KGB’s successor. Smaller memorials took shape in several other cities across the country, while anti-war Russians organised protests outside embassies around the world.

The muted reaction to news of Navalny’s death in most of Russia, however, was a far cry from the huge protests he once led against Putin, underscoring how much had changed in the three years since he returned to Moscow after treatment for a nerve agent poisoning, and was jailed on the spot.

The Kremlin brutally suppressed nationwide protests calling for his release, outlawed his movement and effectively banned all dissent.

Though Navalny remained active in his Anti-Corruption Foundation, now based in exile in Lithuania, and fiercely criticised Putin and the war in letters his team regularly posted on social media, Russia’s totalitarian turn made it all the harder for him to be heard.

“Navalny hadn’t had a voice or a platform for a long time,” a former senior Kremlin official said. “There will be a wave of memorials for him, all sorts of mourning and protest events. They will arrest the activists. And then everything will die out.”

The Kremlin has tried to play down the news. Putin made no comments about Navalny’s death in a series of public appearances in Chelyabinsk, a rustbelt city in the Urals — though he made no effort to suppress a smile. State media received instructions to limit coverage of his death, according to independent site The Insider.

“Putin treated Navalny as a worthless nobody. He did not consider him a dangerous enemy, a pretender to anything. He considered him a petty crook,” said Tatiana Stanovaya, a senior fellow at the Carnegie Russia Eurasia Center.

“He despised him. And the fact that he found himself in such harsh conditions reflected a lot of this contempt of Putin’s. And Navalny simply did not survive it,” she added.

Though the circumstances of Navalny’s sudden death remain unclear, his supporters have accused Putin of being ultimately responsible in any case.

He appeared healthy and in good spirits, though gaunt from 27 stints in solitary confinement, at a court hearing on Thursday, the last known footage of him alive, and during a visit from his mother three days earlier.

The increasingly harsh conditions of his imprisonment, which he had said amounted to torture, meanwhile, had taken a toll on his health.

“It makes sense for them to get rid of someone who could have driven protests in the run-up to the election. The administration knows as well as we do what the real mood in society is, how sick people are of the war and how much they want an alternative,” said Ekaterina Schulmann, a Russian political scientist.

“People might be demoralised, but they won’t love the way things are any more from this. The unhappiness isn’t going anywhere — with the war, with poverty, with repression,” she said.

Navalny’s death is also a serious blow for his foundation, which has attempted to carry out his work from exile through broadcasts on YouTube, the last freely available major social media platform in Russia, and by organising small protests in Russia through an underground network of activists.

Though his team have vowed to carry on his work, the foundation will be “much less functional” after his death, Schulmann said. “He had direct moral authority, and theirs came from him.”

Francis Fukuyama, a professor at Stanford university in the US and a member of the foundation’s advisory board, said losing Navalny’s regular messages, which urged Russians not to give up the fight against Putin with his typical brio, was a particular blow.

“The way that he was treated over the last couple of years was just horrible,” Fukuyama said.

“I guess Putin just wanted to cut it off at the head [ . . .] They’re now scattered all over Europe. And I think there’s going to be a real struggle, you know, for how to keep that group going, because it must be just horribly demoralising at this point.”

Fukuyama suggested that Yulia Navalnaya, who largely shunned the spotlight during most of Navalny’s career, and his daughter Daria were best suited to carry on his legacy.

“There’s nobody, I think, that’s capable of filling his shoes even remotely,” Fukuyama said.

“[Yulia] is a very strong willed woman, so maybe she can take up the torch. But it’s going to be very, very hard. He had a unique sense of humour, and he was able to say things that were appealing to ordinary people in a way that a lot of other opposition figures were not. Whether she’s got any of that ability, we’ll have to see.”

Additional reporting by Guy Chazan in Munich