Sadly, the dictatorship of Libya's Muammar Gaddafi (or al-Gaddafi), is not guaranteed to fall. Muammar grabbed power in a military coup in 1969 when he was only 27 years old. While admitting he is a pretty remarkable man, going from poor Bedouin born in a tent to dictator of a nation in a very short time, there is little else good to say about him. He was a noted anti-imperialist, which is well and good, but that is not an excuse for crushing the life out of the people of Libya.
Gaddafi could have just abdicated, but he chose instead to kill as many people as necessary to maintain his power. He's an old buzzard now, 68 years old, but if he can kill enough people he might hold onto power and live another couple of decades. Sadly, uprisings often don't work against the most ruthless dictators. A lot of factors come into play.
Chiang Kai-shek was as ruthless as they come. We are taught to hate the war crimes committed by Japanese militarists in China before and during World War II, but Chiang actually killed far more of his own people than the Japanese did. He got the boot from the Chinese Communist Party, only to take over Taiwan and crush it under his heal. He was still in charge of Taiwan when he died. He was a U.S. sponsored dictator.
General Francisco Franco was the most Roman Catholic, fascist dictator of Spain from 1936 until his death in 1975. He should have gone to the gallows with Hitler's crew, but the U.S. security establishment was more afraid of another dictator, Joseph Stalin of the Soviet Union, when Germany was finally defeated. So Franco kept murdering people until the day he died, with U.S. support. The U.S. got to put some air bases in Spain in return.
There have been successful, and failed, revolutions against both left-wing and right-wing dictators. There have been a surprising number of dictators and monarchs who allowed or even encouraged democracies to develop and replace them. England, after all, evolved from a mainly monarchist to a mainly democratic system. Some monarchs cooperated with the process, others resisted. One, Charles I was beheaded by order of Parliament; another James II, was deposed in the Glorious Revolution of 1688.
For dictators force of arms does not insure success, defined as keeping a hold on power, but failure to slaughter, or at least imprison, opponents is a guarantee of failure. Often the opponents are not about to establish a democracy, but want to replace one dictator with another. The overthrow of the Fulgencio Batista by Fidel Castro in Cuba in the 1959 is as good example of that as any.
Republics (which allow a limited set of citizens to elect their leaders, as in the original U.S.A.) and democracies don't have a monopoly on goodness. Nor are all dictators all bad all of the time. What allowing a large group of citizens to share in power does is allow for flexibility and growth. With few exceptions, the type of person who aspires to, and obtains, a dictatorship has a pretty inflexible mindset. That means creativity and experimentation gets stifled. Sure, a Napoleon Bonaparte or Joe Stalin might promote scientific advancement, and sometimes a central command can jump start an economy, as Hitler and others showed. But in the long run thought, culture, and business become inflexible under dictators and start losing out to more flexible systems.
Muammar Gaddafi's real power came not from any particular brilliance but from oil. The great powers, corporations as well as nations, wanted Libyan oil, and were willing to leave Gaddafi in place as long as the oil and its profits flowed. The same is true of the Saudi dictatorship.
I hope Gaddafi is overthrown by the people of Libya, not by intervention from Europe or the U.S. However, I won't be surprised if he again manages to kill everyone who disagrees with him. Sadly, if that happens, it will encourage other dictators to reply to popular yearnings for freedom with bullets, not reform.