Holed up in the last major rebel stronghold or unable to return home after fleeing abroad, they are frustrated to have been abandoned by the international community.
"Today, I'm looking for a homeland," activist Shady Matar told AFP from exile in neighbouring Turkey.
"I can't go home while the regime is still in power," said the 27-year-old, whose hometown of Daraya near Damascus was retaken by the government in 2016.
And "most countries whose governments say they support the Syrian people have closed their borders" to us, he said.
Sparked by the brutal repression of anti-Assad protests in 2011, the conflict has killed more than 360,000 people and displaced millions at home and abroad.
But fighting has failed to topple Assad, endless diplomatic efforts have been unable to reach a peaceful transition, and the regime now appears stronger than ever.
With backing from Russia and Iran, the government has expelled rebels and jihadists from large parts of Syria, and now controls almost two-thirds of the country.
The government also looks set to increase its influence in a large swathe of territory under Kurdish-led control, after the shock announcement last month of a US military pullout.
- 'The criminal may win' -
On the diplomatic front, efforts seem underway to bring the Damascus regime back into the Arab fold after years of frosty relations.
The Arab League suspended Syria's membership in November 2011 as the death toll mounted and several regional powers bet on the demise of the Assad regime.
But Sudan's president last month made the first visit by an Arab leader to Damascus since the start of the conflict.
The United Arab Emirates last week reopened its embassy in the Syrian capital, and fellow Gulf state Bahrain has followed suit.
Bilal Bayush, a media activist in the last major rebel stronghold of Idlib, said he was not surprised.
"Their interests with the opposition have ended, and they now have interests with the Assad regime," he said.
Political opposition chief negotiator Nasr al-Hariri was outraged.
"While our people are dying of cold in refugee camps drowning in cold winter rain, some of our Arab brothers are racing to open up to the criminal who is responsible," he said last week on Twitter.
"Yes, Bashar the criminal may win, he may triumph in the face of the colluding international community," he wrote.
"But he has not and will not defeat the will of the free Syrian people."
He said a solution in Syria required "a real political transition and holding the criminals to account".
Endless rounds of UN-brokered peace talks have failed to stem the bloodshed and have been overtaken by a parallel track led by Moscow, Tehran and rebel backer Ankara.
- Revolution 'orphaned' -
The armed opposition is faring no better on the ground.
In Idlib, rebels and jihadists have been hemmed in by a buffer zone under a September deal between Russia and Turkey to avert a massive regime offensive there.
It was the latest agreement to be reached under the Russia-Iran-Turkey negotiations track.
Analyst Nawar Oliver said the opposition -- both political and armed -- was in dire straights.
"The military opposition has no choice except to follow what is decided on an international level," said the analyst at the Turkey-based Omran Center.
It must do this "to preserve what it still has", he said.
Naji Mustafa, a spokesman for the Turkey-backed National Liberation Front rebel group in Idlib, said the international community had dropped the Syrian opposition.
"The revolution has been orphaned," said the 38-year-old, who defected from the Syrian army in 2012.
"The whole world abandoned it."
But in the town of Azaz, close to the Turkish border, lawyer and human rights activist Muthana Nasser was determined years of death and destruction would not go to waste.
"The sacrifices and suffering of Syrians will not be in vain," he said.
Whatever the final outcome, "I will tell my children when they grow up about the greatest revolution in contemporary history," said the father of three.
I will recount "how the international community watched the bloodshed of innocents only to denounce it and not intervene to stop the massacres," he said.