Faisal al-Qudsi, the son of a former Syrian president, said that while President Bashar al-Assad's government would fight to the end, the military action could only last a further six months and then there would be "millions of people on the streets."
The report came amid reports of renewed violence in the Syrian capital.
According to Reuters, Syrian security forces fired on a huge protest against Assad's regime linked to the funerals of three youths killed a day earlier during mass demonstrations.
"They started firing at the crowd right after the burial," a witness told Reuters by telephone.
One mourner was killed and four wounded, the opposition Syrian Revolution Coordination Union reportedly said.
And gunmen assassinated a senior prosecutor and a judge in restive northwest Syria on Sunday, the Associated Press reported citing Syria's state news agency.
Gunmen opened fire on a car carrying Idlib provincial state prosecutor Nidal Ghazal and judge Mohammed Ziadeh, SANA reported, adding that the two were killed instantly.
Bloomberg, meantime, cited a statement by the UK-based opposition Syrian Observatory for Human Rights as saying that at least 13 people were killed on Saturday in Homs, and 31 on Feb. 17.
The violence came as China's Vice Foreign Minister Zhai Jun urged Damascus to halt the fighting and restore stability in Syria.
Zhai, speaking in the capital after a meeting with Assad, backed the Syrian leader’s proposed referendum on the Constitution, set for Feb. 26, and future elections.
"We hope that the referendum on a new Constitution as well as the forthcoming parliamentary elections pass off calmly," Zhai said, Britain's daily Telegraph reported.
"The position of China is to call on the government, the opposition and the rebels to halt acts of violence immediately."
Xinhua, China's official news agency, meantime expressed the view that it was still possible for the Syrian crisis — which has claimed thousands of lives — to be resolved peacefully.
"China believes, as many others do, there is still hope the Syria crisis can be resolved through peaceful dialogue between the opposition and the government, contrary to some Western countries' argument that time is running out for talks in Syria," Xinhua wrote in an English-language commentary.
"Among Syria's assorted opposition groups, some have voiced a willingness to hold dialogue with the Syrian government and also warned those seeking outside intervention against becoming a tool of the West."
A BBC correspondent in Beirut, meantime, said a number of well placed people — including Americans — had expressed the belief that economic factors would bring regime down, using the warning from Qudsi as an example.
Qudsi is heavily involved in Syria's economic liberalization "and from a family with a long political tradition," the BBC reports, lending weight to his assessment that the business community was deserting the regime.