Now that hob-nailed boots repression has stifled, although not ended, the street protests there are three paths that Iran can head down.
The Constitutional Alternative
The Assembly of Experts overturns the obviously fraudulent election and deposes both Ahmadinejad and Grand Ayatollah Ali Khamenei. Within Iran's constitutional hierarchy the Assembly of Experts is above Guardian Council which has already certified the stolen election. I don't hold out high hopes for this alternative.
The Pinochet Alternative
Backed by the army and the Basij militia, Ahmadinejad engages in a Reign of Terror to solidify his hold on power. While some people are murdered on the streets many thousands more simply disappear into torture chambers or shallow graves.
The Gdansk Alternative
The protests move from the streets to the economy. Strikes, worker slowdowns, sabotage, and foreign boycotts brings Iran's government to its knees. Faced with having to kill a third of its population to maintain order, the government capitulates to the public.
I don't know Iran well enough to lay odds on any particular outcome. My guts says that Ahmadinejad is willing to go the route of mass murder and willing to turn his entire country into a massive Abu Ghraib prison.