While world powers such as the United States, France and Britain refuse to have anything to do with a leader the French prime minister described as a "butcher", the question is increasingly being raised within these countries.
Staffan de Mistura, the UN envoy for Syria, echoed this feeling this month when he said Assad was "part of the solution" to end a conflict that has killed more than 210,000 people, displaced nearly half the country's population and spilled over into neighbouring nations.
And this week, a private trip to Damascus by French lawmakers who met Assad for talks drew an angry response from the French government which cut diplomatic ties with Syria in 2012 -- but was feted by media in the conflict-torn country.
"The Assad regime is trying to give the impression of unstoppable momentum towards normalisation of ties," said Shashank Joshi, senior research fellow at Britain's Royal United Services Institute defence and security think-tank.
But he said this was "exaggerated" and that while Western and Syrian intelligence agencies may have had low- to mid-level contacts, there had been no formal coordination.
- A softening stance? -
Officially, the United States -- like France and Britain -- remain steadfast in their demand that the Syrian leader quit power.
But repeated diplomatic attempts at a solution to the conflict have failed, and Western governments are coming under increasing pressure from intelligence services who are worried about the number of nationals joining the ranks of IS.
International coalition strikes against the jihadist group that controls swathes of Iraq and Syria, meanwhile, have produced mixed results and some countries appear to be softening their stance towards Assad.
In the United States, experts say there have been signs that Washington may be considering abandoning efforts to unseat the Syrian leader in any future transition.
Yezid Sayigh, senior associate at the Carnegie Middle East Centre, said recent consultations with Russia -- a fervent Assad ally -- "suggest an effort to devise a new diplomatic framework jointly with Russia that would allow the US a face-saving means to accommodate Assad's survival more formally."
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In a joint statement published Friday by newspapers Le Monde and Al-Hayat, the French and British foreign ministers stressed Assad could not "credibly" be part of any future government fighting IS.
But French Senator Francois Zocchetto, one of the lawmakers who met with Assad, argued Friday that it was impossible to fight against extremism in France while ignoring what was going on in Syria.
"This secular state could disappear tomorrow... because right now there is no longer any moderate Syrian opposition," he said.
- Syria opposition roadmap -
As if on cue, though, Syria's main domestic and exiled opposition groups said Friday they had for the first time agreed a draft crisis roadmap that incorporates a call for a transitional governing body.
But while the exiled Syrian National Coalition insists Assad must step down in any peace deal, the domestic National Coordination Committee for Democratic Change (NCCDC) has been more circumspect.
One of the documents on which the roadmap is based calls for any transitional governing body to have full executive powers, but does not specify Assad's role.
Nevertheless, Petra Becker, a Syria expert at the German Institute for International and Security Affairs think-tank, said the mere fact that both opposition groups were talking was positive.
She said IS had "put pressure on the opposition to come to an agreement."
Many experts say that formally re-engaging with Assad would be a mistake.
"Western countries have cobbled together a very successful Arab coalition (to fight IS) and that coalition would fall apart," said Joshi.
He added that much of the focus was on the Sunni community in Syria, which forms the backbone of the rebellion against Assad and is widely considered as key to tackling IS from within.
"If you join hands with the primary persecutor and tormentor of Syria's Sunni community, you jeopardise that chance and you encourage people to join ISIS (IS) in greater numbers," he said.