Why is Iran's theocracy tumbling down?

The last Shah of Iran had a dream ... to permanently put his country on the list of the ten most industrialized nations in the world. Alas, his greatest mistake was to pursue this dream on the expense of his people's freedom and beliefs, so everything crumbled in 1979 with the Islamic revolution.
The main question that remains is why the people of Iran decided to overthrow an autocracy so to replace it with a theocracy, since both regimes constitute an enormous lack of freedom and both are antagonist with the values of democracy. Well, the major reason for the revolution was the ever growing despotism perpetrated by the Shah against his own people together with a huge mistake which was to continuously underestimate the power of the ayatollah's supporters until it was just too late to contain the widespread manifestations. Furthermore, Shah Reza Pahlavi was a westernized monarch that wanted to secularize Iran so to bring it closer to European standards. This only contributed to the growing discontent of the masses, which saw their king as a puppet of the west who continuously disrespected the cultural identity of his nation so to reinforce his vision of a perfect modernized society. Imagine what it would be if, for example, a british prime-minister decided to implement a vigorous and fundamentalist catholic regime in Britain ... surely it would lead to massive demonstrations of discontent. The other way around explains what ended up happening in Iran.
Now that 20 years have passed since the Iranian Revolution, the revolutionary fervour has all but evaporated and the dominant system is generating more contestation than support. In fact, it seems Iranians have grown tired of living under the rules of a clerical doctrine. Why, we ask?
The main reason is demographics. About two thirds of Iran's inhabitants are 25 years old or younger, which means that few Iranians have lived the revolution or were just to young then to keep any sort of significant memory of its ideals today. More and more Iranians have families abroad and nowadays' technology provides an unparalleled access to information, so many youngsters are growing ever more conscious of how life is abroad and how their lives are within the boundaries of their own country.
Another very important factor is that the ayatollahs' regime saw in George W. Bush the opportunity it needed to harden itself, on the basis of the menace which was supposedly growing across the pond. Now that George Bush's radicalism was replaced by a much more conciliatory Obama, the regime no longer has a scapegoat to justify their fundamentalist doctrine.
Moreover, Iran is no longer surrounded by enemies. The Soviet Union has imploded and Iraq has been overpowered, so the lack of enemies makes an aggressive regime much more difficult to gather popular support.
But what is causing a devastating blow in the regime is the fragmentation of its own core, with a growing amount of clerics and politicians turning a lot more towards the reformist and more moderate side, thus giving psychological strength to all of those who are unhappy with the way things are.
The regime is now holding a firm grasp to the nuclear program, since this is the only thing that nowadays can be used by President Ahmadinejad as propaganda against the west and to still keep the potential Israeli threat very much alive. Nevertheless, the program is failing to gather enough support so to counterbalance the momentum all reformists are enjoying now.
Anyway, being Iran a massively populated country according to Middle East standards, counting with nearly 80 million inhabitants, this means that tens of millions of Iranians are still fond of their regime, and it is from within this group that the recruits for the Revolutionary Guard are chosen. Hence, the military power is on the hand of hardliners who will make a change of things quite difficult, which means that the Islamic regime will not fall without massive bloodsheds.
Only time will tell if Iran is on the brink of social retransformation. Most likely the Shah's heir will not be called back like a returning messiah, but probably the regime will be forced to reinvent itself just enough to reduce the calling power of those who claim some change.
May the Persian pride be retrieved from the mists of obscurantism and return to its former glory in a modern and democratic way.