I am among those who think that protracted conflict is the more likely scenario for the years to come, but I don't think that it is because the situation isn't "ripe". I don't think that mutually hurting stalemate/ripeness could ever apply to the Syrian conflict because of its zero-sum game nature for the incumbent sides (i.e. the Asad clan and Iran). Ripeness can lead to a conflict resolution when there is a cake that can reasonably be divided (tellingly, the Middle Eastern examples Zartman used in his talks were cases of inter-state territorial conflicts, not revolutionary wars). In the present case, no such division can be envisioned by either the Asad clan, that cannot reasonably hope to survive a power-sharing arrangement (even if members of the current regime or recent defectors can); even in the Yemeni scenario, Saleh had to go), nor Iran, which is not defending a degree of influence in Syria, but strategic assets that would not be secure under any other regime.
Dr Thomas Pierret is a Lecturer in Contemporary Islam, Islamic and Middle Eastern Studies, University of Edinburgh