As nice as it all sounds, its obvious that our previous systems, beautiful and elegant as they were, were (i) not without flaw and (ii) impractical in the 21st Century. Please feel free to argue otherwise, but a kingdom today would have many problems. With the treacherous side-by-side advance of intellect and selfishness people are just not concerned with the wellbeing of anyone but themselves, let alone a set of other families. The Kingdom would be corrupt; rich king with a bunch of wives, poor families. It would be better than rich President, poor people who are brainwashed into thinking that somehow, a piece of paper they placed in an already pre-set ballot resulted in their present way of life. Like they chose this person to rule them, like they chose to live under the pretense of free-ness. But it's still not a drastic improvement.
You have to guess that Marxism came in at least somewhere in my considerations. It has to. Regardless of your personal feelings, you can't help but consider the Manifesto... it's genius. I figure it wouldn't work too well because there's too much room in the system to change things. Think Animal Farm (George Orwell). Governments don't usually follow a theory they didn't make up themselves to the T. This leaves a 'heory' which frankly is just not the same thing. In all seriousness though, as one aspect of equality becomes exception to the rule, its hard to hold tight reins on the others without looking like the very same government the people were trying to escape by revolting.
Egypt is currently trying to get a revolution going, and more power to them. But the effects, longterm effects are not certain. People sometimes get so riled up trying to get rid of the current failures that they do not foresee the future catastrophe lying ahead. Anyway, we hope for the best for Egypt.
Maybe the mother of all government styles will turn out to be a well ground mix off all the possibilities. Perfect government is attainable only by God, so we are not going to reach that, but its not too far-fetched to just look for something that works for us.