Rob Malley and Hussein Agha, in a NYRB essay well worth reading for its many insights into the regional situation — most notably that it will continue to be extremely chaotic and could well result in a regional war — offer a grim prognostic about revolution:
Revolutions devour their children. The spoils go to the resolute, the patient, who know what they are pursuing and how to achieve it. Revolutions almost invariably are short-lived affairs, bursts of energy that destroy much on their pathway, including the people and ideas that inspired them. So it is with the Arab uprising. It will bring about radical changes. It will empower new forces and marginalize others. But the young activists who first rush onto the streets tend to lose out in the skirmishes that follow. Members of the general public might be grateful for what they have done. They often admire them and hold them in high esteem. But they do not feel they are part of them. The usual condition of a revolutionary is to be tossed aside.
The Arab world’s immediate future will very likely unfold in a complex tussle between the army, remnants of old regimes, and the Islamists, all of them with roots, resources, as well as the ability and willpower to shape events. Regional parties will have influence and international powers will not refrain from involvement. There are many possible outcomes—from restoration of the old order to military takeover, from unruly fragmentation and civil war to creeping Islamization. But the result that many outsiders had hoped for—a victory by the original protesters—is almost certainly foreclosed.
I think he's wrong, or rather than this is an unnecessarily pessimistic view of the long-term processes unleashed by what happened this year. Things could get very grim, especially in Yemen and Syria, but the picture is not one of universal despair.