[1] http://en.wikipedia.org/wiki/2011_military_intervention_in_L...
[1] http://en.wikipedia.org/wiki/2011_military_intervention_in_L...
In the current state of the US, however, the political will for new military action is fairly minimal, for better or for worse.
The US would only have to make Assad think it was serious about another Libya in order to give him some serious misgivings. Get NATO to make some rumblings, which would encourage Chavez to issue one of his proclamations against American Imperialism, then make a backroom deal to get Assad out.
At the end of the day, the Bush Doctrine of democracy-at-swordpoint is simply ineffective. There exists, however, the very real possibility of using soft/"firm" power to encourage the outcomes you want.
1) The Assad family would have to find the threat from NATO credible. 2) They would have to believe that there is no chance of defeating the rebels militarily and outlasting NATO bombardment. 3) The major power players in the Assad government would have to be willing to accept life in exile, with no opportunity for travel or engagement with the rest of the world. (Even Ben Ali, the dictator who left Tunisia semi-voluntarily, has an international warrant out for his arrest.) 4) Some country (presumably America) would have to be willing to either pay them a significant lump sum out of their own pocket or allow them to loot Syria before they leave.
You could pick any one of these apart.
Not that I agree with the idea of paying off people, but Syria's total GDP is only about US$60 billion, hard to imagine that it would take "trillions".
2) What if the national leader you're trying to pay off believes himself to be a true partiot and refuses to surrender his country to US interests?