What are the Ten Kings?

''Three Rings for the Elven-kings under the sky,


Seven for the Dwarf-lords in their halls of stone,
Nine for Mortal Men doomed to die,
One for the Dark Lord on his dark throne,
In the Land of Mordor where the Shadows lie,
One ring to rule them all, one ring to find them,
One ring to bring them all and in the darkness bind them
In the Land of Mordor where the Shadows lie.''

You might ask, what does Tolkien's Lord of the Rings have to do with the Ten Kings?  Actually, Tolkien drew heavily from the Bible and Biblical themes in his writings.  From the Book of Daniel - Chapter 7:
After that, in my vision at night I looked, and there before me was a fourth beast—terrifying and frightening and very powerful. It had large iron teeth; it crushed and devoured its victims and trampled underfoot whatever was left. It was different from all the former beasts, and it had ten horns.
There are ten powerful rulers (not necessarily called a king, but someone who rules like a king).  They are disparate rulers, but like the "True Ring" they will be become like the Nazgul and be bound to serve one master.
While I was thinking about the horns, there before me was another horn, a little one, which came up among them; and three of the first horns were uprooted before it. This horn had eyes like the eyes of a human beingand a mouth that spoke boastfully.
Of these 10 kings, three of them are destined to be 'de-throned'.  This could mean being defeated in war, or they could simply make themselves vassals of this new King (AntiChrist or Mahdi, depending on which eschatology you're following).

If, for discussion, we assume that 3 of the 'kings' are the leaders of Iran, Iraq, and Saudi Arabia falling in line behind the Mahdi then the formation of the Caliphate we are currently witnessing makes sense.

What about the fall of the governments of Egypt, Lybia and now Syria?  Could they be the 3 kings being supplanted in deference to the Caliphate?

So, who are the other 7?