About 8% of Iranians are of retirement age now. But Iran’s fertility has fallen from seven children per female at the time of the 1979 revolution to around 1.6 at present. When today’s bulge generation of young people reaches retirement age, there will be few children to support them, and by mid-century a third of all Iranians will be elderly dependents. Nothing like this sudden shift form pre-modern to post-modern demographics ever has happened. Rich Western countries may not survive the graying of their population. For Iran, with US$4,000 in personal income per capita, low fertility is a national sentence. President Mahmud Ahmadinedjad called it “genocide against the Iranian nation”.
Just when Iran most needs hydrocarbon revenues, its oil output will decline sharply. Natural gas exports can offset the decline to some extent, but not entirely. Iran’s only chance of survival lies in annexing oil-rich regions on its borders: Bahrain, Iraq’s Basra province, parts of Azerbaijan, and ultimately Saudi Arabia’s Shi’ite-majority Eastern Province. That is why Iran needs nuclear weapons.
Of course, Iran can’t annex more Persians, which is why the whole thing is moot. That’s not to say the time between now and Iran’s demographic exhaustion will be anything like peaceful.