I just don't think Syria is "flippable" and it is related to why they are less likely than pro-American autocracies to crack under the pressure of the unrest stirring in the Arab world.
Strategypage notes that Syria is tougher to destabilize because their military is willing to commit mass murder (the key decision in my view about whether people power can topple autocracies) in support of the regime (recalling the near razing of the city of Hama a few decades ago, although to be fair, do we know that the military's troops would obey a similar order today?) and the genuine popularity of Boy Assad based on anti-Israeli policies. I noted the anti-Israeli nature of the regime and why that pillar of the regime means that outreach to the Syrian government won't work. Why would Assad trade a pillar of their regime for our friendship when our anger with them is fairly harmless?
I'd add another factor that makes Syria more ruthless--the government's status as an Alawite (a Shia variation that has less credibility as being truly Moslem as Shias do in Sunni eyes) minority government in a majority (3/4 of the people) Sunni state. Losing control could mean sectarian divisions would result in a bloodbath of the majority against the losing minority. That is strong incentive to do what it takes to stay on top.
Still, one never knows how deep the popularity of Assad runs and what might trigger popular anger that makes their apparent "stability" evaporate as surely as it did in Tunisia. Defeat in a war with Israel might do it after decades of anti-Israel propaganda raised expectations of driving the Jews into the sea.
Which is a strong reason for Syria to keep out of a direct war with Israel and hope support for Hezbollah and Hamas is enough in the short run to keep their anti-Israel actions at a high enough level to meet public expectations.
Also, one never can tell when the failure of Assad to order his troops to drive the Jews into the sea will make his anti-Israel propaganda seem fairly hollow to the people. Could a popular revolt there be driven by anti-Israeli opinion rather than a yearning for freedom? That makes the Iranian alliance useful in that it leaves the possibility open that Iran will directly attack Israel with nukes and take care of the Israel problem for Damascus and allow Assad to bask in reflected (and radiated) glory of siding with the goons that did the dirty deed.
So how likely is it that we can persuade Assad to "flip" to our side out of gentle, persuasive outreach?
None at all, if my point isn't clear. I'm open to flipping Syria. But it will only be done out of fear in Damascus of maintaining their current policies and hope that flipping can save them from utter destruction. Only a nutcracker can crack a nut.