Among the many moments of celebration across Syria on Sunday, the scene at the Umayyad Mosque in Damascus may be remembered as one of the most significant.

Abu Mohammed al-Golani, the leader of Hayat Tahrir al-Sham (HTS), who led his opposition forces out of Idlib province and in just 11 days dealt the fatal blows that drove President Bashar al-Assad from office, stood in front of a cheering audience.

"This will be a new victory for the entire Islamic nation, this will be a new historic victory for the region," al-Golani said as those in the crowd pumped their fists.

But precisely what al-Golani, 42, a one-time adherent to al-Qaeda whose group remains listed as a terrorist entity by many Western nations, has in mind for Syria — and whether he can retain control of the dynamic situation — are among the many unknowns now confronting Syrians.

Assad and his father before him ruled the country for more than 50 years, killing or imprisoning anyone who challenged the family dynasty.

Humanitarian groups say Assad's forces murdered more than 300,000 opponents and imprisoned countless thousands more in the aftermath of the Arab Spring protests of 2011.

Even in cities such as Latakia, which remained loyal to Assad, there were celebrations, suggesting there is widespread relief that he is finally gone. But what kind of government or leader he should be replaced with was always going to be contentious.

Who takes over?

Al-Golani's remarkable success at spearheading the military take-out of Assad's Syrian Arab Army now puts him at the forefront of the people being talked about as a possible successor.

"I think it's a new era," said Fawaz Gerges, a Middle East analyst at the London School of Economics.

"Syria could go two ways. It could descend sadly and tragically into all-out social, political and ethnic violence or could basically begin the process of social healing."

Whether al-Golani is positioning himself to be that healer remains to be seen, but already he's shown himself to be adept at the kind of public relations the job would require.

In the hours after HTS seized Syria's second-largest city, Aleppo, he reportedly issued orders that there were to be no recriminations against supporters of Assad, nor should minorities feel threatened.

In an interview with CNN, he wore a plain green military uniform devoid of any overt religious symbols, and said his only goal was to rid the country of Assad.

A social media post by HTS even referred to him by his given name, Ahmad Al-Shar'a, rather than by his nom de guerre.

Since 2017, al-Golani and HTS have ruled Syria's Idlib province next to Turkey, controlling border check points, running a municipal-style government and carrying out de-facto international relations with countries such as Turkey.

Extremist roots

In his rare interviews, al-Golani has said he publicly cut ties with al-Qaeda in 2016 and now focuses on governance,  rather than plotting attacks on the West.

But some observers question whether he can translate his experience of governing a small pocket of Syria into the immensely more difficult task of running a complex country with all of its competing religions, ethnicities and political agendas.

"As the geographic scope of this expanded nationally, I think it will probably become more difficult for HTS and for al-Golani to realistically steer it," said Sam Heller, a Beirut-based researcher for the think-tank Century International who has studied the area's extremist groups.

"I wouldn't assume that he's going to be in control now."

Heller said the speed of the collapse of Assad's regime was so sudden and swift that al-Golani himself may have been surprised he ended up leading his forces into Damascus.

Initially, the offensive he launched from Idlib toward Aleppo appeared to be more of a strategic move to improve HTS's front-line positions than a national movement of liberation.

"It's hard to know what Golani's bedrock principals are," Heller said.

Others question whether his stated transformation away from jihadi ideology into a political moderate is truly sincere.

"When the Taliban took over Afghanistan in the 1990s, they promised exactly the same thing," said Sajjan M. Gohel, international security director at the Asia-Pacific Foundation in London.

"They promised peace, security, modernity, and then they ruled in a very draconian way. HTS is going to have to prove itself."

Turkey's win

The one foreign leader who appears to be in the strongest position to influence whatever happens next in Syria is Turkey's Recep Tayyip Erdogan.

The Turkish president has played the long game with Syria over many years, bankrolling and supplying military aid to opposition groups, as well as allowing more than three million Syrians who fled the civil war to shelter in Turkey.

As al-Golani's troops swept south, many of the opposition groups backed by Turkey went with them.

"The Turks will try to consolidate or expand their influence in Syria," said Heller, the Century International analyst.

"Their supreme interest in Syria has been the defeat of the PKK-linked SDF," he said, referring to the Syrian Democratic Forces.

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The PKK, or Kurdistan Workers' Party, is a Kurdish separatist group considered a terrorist organization by Turkey and some Western governments, including Canada. It's blamed for attacks on Turkish soldiers and civilians.

The United States backs the Syrian Democratic Forces, which Turkey claims is linked to the PKK. In one of the Biden administration's first statements on the demise of Assad, a spokesperson indicated that support would remain, without any mention of Turkey.

Notably, as HTS and other opposition forces were closing in on the Syrian cities of Homs and Damascus, other Turkish-backed rebels went in the other direction to attack Kurdish positions in the north and east, including the northern city of Manbij.

While HTS's links with Turkey are more nebulous, there have been multiple reports that Turkish military consultants helped with drone training, logistics and other support — suggesting that whatever faction eventually dominates in Damascus, it may be sympathetic to Turkey's wishes.

Few contenders

As for other possible contenders to take over from Assad, few analysts who spoke to CBC News were willing to make a guess.

"I think the answer is probably no one. That's my concern," Heller said.

Others said the messaging al-Golani's group sends over the next few days will be crucial.

"So far, we have seen about 400,000 displaced people from Aleppo and Hama and Homs," said Gerges of the London School of Economics. "Reassuring the Syrian people that the rebels will not exact vengeance against the Syrian people, this could be really a major turning point for Syria."

Gohel of the Asia-Pacific Foundation said the decisions Syrians will make in the days and months ahead are unprecedented for their country.

"In terms of what happens next, we are entering uncharted territory."