Perhaps they could grow to the point where they can make an alliance with the US (we would do it for strategic reasons, like in the case of Saudi Arabia). There would be a re-branding into the "Free Syrian Republic" or some such, and the buy out would be complete. Assad out of power, oil controlled by the US. It's what we wanted back when we gave ISIS (then known as the "Free Syrian Army") their initial startup capital and weaponry.