The first three versions of regime change during the Arab Spring - unhindered escape of the Tunisian President, imprisonment and criminal proceedings in Egypt and mob law in Libya - have created a momentum that will be hard to stall.
The case of Libya shows that decisive action, i.e. Cameron and Sarkozy's initiative - supported by Obama - to effect NATO deployment, sealed Gaddafi's fate.
Otherwise it could have led to civil war and perhaps even the survival of the dictator. Yemen's dogged dictator is now heavily at risk.
However, the most bloodthirsty of all dictatorships, the Assad regime in Syria, keeps on fighting unperturbed because it seems to be sure of the protection by some weighty allies.
Iran's financial assistance and weapons supplies; Turkey's dubious stance which, on the one hand, calls for moderation but would not welcome regime change; and most of all, Russia's support at the United Nations give Assad enough reason to rage on.
Key words such as regime change, democratic renewal, freedom of the press are not well liked in Moscow and Beijing which seek to prevent any military intervention of the West.
Compared to Gaddafi, father and son Assad have to answer for at least 50,000 deaths and cannot rely on the kind of loyalty Gaddafi received from his tribesmen until the end.
A Libyan style involvement of the West and NATO as protectors of the civilian population in Syria would definitely sweep away the Assad regime. At the same time this would mean a heavy blow for Teheran which organises its assistance for Hezbollah in Lebanon and for Hamas in the Gaza strip from Damascus.
The Arab monarchies Morocco and Jordan might contain revolutionary elements but the majority of its people are Royalists. Both dynasties are held to be the descendants of the prophet Mohammed.
Saudi Arabia has a key position. The monarchy - closely linked to the clergy - does not only feel more secure on the domestic front but thinks it can rely on US protection.
After the death of the heir to the throne, Prince Sultan, this week a newly constituted High Council of Princes will now determine the succession to the aged King Abdullah. New arrangements will for the first time allow that not only members of the founding generation but also grandchildren and nephews of Ibn Saud obtain the right to be elected.
The oldest of the heirs apparent and current Minister of the Interior, Prince Nayef, is seen as a hard-line traditionalist who has little understanding of the spirit of the time.
Those Arab experts in the know are betting on a younger, more progressive Prince; a solution that would suit the ailing but realistically thinking King Abdullah.